Saturday, 23 May 2026

Smith Number Subsets

Smith numbers have the property that the sums of their digits are equal to the sums of the digits of their prime factors with multiplicity. Based on that criterion, the number associated with my diurnal age today, 28174, is a Smith number:$$28174=2 \times 14087$$This number however, has a further property if you look at it closely. The number and its prime factors share the same digits with the exception of the zero. This qualifies it for membership in OEIS A176670:


A176670
: composite numbers having the same digits as their prime factors (with multiplicity), excluding zero digits.

The initial members of the sequence are:

1111, 1255, 12955, 17482, 25105, 28174, 51295, 81229, 91365, 100255, 101299, 105295, 107329, 110191, 110317, 117067, 124483, 127417, 129595, 132565, 137281, 145273, 146137, 149782, 163797, 171735, 174082, 174298, 174793, 174982, 193117, 208174, 210181, 217894

The table below shows the details:

  number   digit sum   factors         sum of factors' digits

  1111     4           11 * 101        4
  1255     13          5 * 251         13
  12955    22          5 * 2591        22
  17482    22          2 * 8741        22
  25105    13          5 * 5021        13
  28174    22          2 * 14087       22
  51295    22          5 * 10259       22
  81229    22          29 * 2801       22
  91365    24          3 * 5 * 6091    24
  100255   13          5 * 20051       13
  101299   22          11 * 9209       22
  105295   22          5 * 21059       22
  107329   22          29 * 3701       22
  110191   13          101 * 1091      13
  110317   13          107 * 1031      13
  117067   22          167 * 701       22
  124483   22          281 * 443       22
  127417   22          47 * 2711       22
  129595   31          5 * 25919       31
  132565   22          5 * 26513       22
  137281   22          107 * 1283      22
  145273   22          53 * 2741       22
  146137   22          317 * 461       22
  149782   31          2 * 74891       31
  163797   33          3 * 71 * 769    33
  171735   24          3 * 5 * 107^2   24
  174082   22          2 * 87041       22
  174298   31          2 * 87149       31
  174793   31          47 * 3719       31
  174982   31          2 * 87491       31
  193117   22          113 * 1709      22
  208174   22          2 * 104087      22
  210181   13          101 * 2081      13
  217894   31          2 * 108947      31

What's interesting is that these same digits show up several times in the above table:

  • 17482 which is a permutation of the digits of 28174
  • 149782 which has the digit 9 added to the permuted digits
  • 174082 which has the digit 0 added to the permuted digits
  • 174298 which has the digit 9 added to the permuted digits
  • 174982 which has the digit 9 added to the permuted digits
  • 208174 which has the digit 0 inserted after the 2 in 28174

All these numbers are xenodromes meaning that they have no repeated digits.

The obverse of this is to find all Smith numbers that have NO digits in common with their prime factors. There are 72 of these in the range up 40000 (permalink):

4, 27, 58, 166, 454, 576, 588, 627, 648, 654, 666, 690, 706, 729, 1449, 1858, 1908, 2067, 2409, 2839, 4369, 4414, 4464, 4880, 4960, 5458, 5818, 5854, 6084, 6096, 6567, 6583, 6684, 6718, 6760, 6880, 7068, 7078, 7186, 8158, 8568, 8680, 8864, 8901, 9166, 9414, 9849, 10669, 10786, 10966, 14458, 14566, 14958, 15646, 15709, 15984, 16546, 16866, 17496, 17664, 17718, 17840, 18418, 18454, 19818, 20229, 20299, 22509, 26727, 33680, 33760, 33880

The table below shows the details:

  number   digit sum   factors              sum of factors' digits

  4        4           2^2                  4
  27       9           3^3                  9
  58       13          2 * 29               13
  166      13          2 * 83               13
  454      13          2 * 227              13
  576      18          2^6 * 3^2            18
  588      21          2^2 * 3 * 7^2        21
  627      15          3 * 11 * 19          15
  648      18          2^3 * 3^4            18
  654      15          2 * 3 * 109          15
  666      18          2 * 3^2 * 37         18
  690      15          2 * 3 * 5 * 23       15
  706      13          2 * 353              13
  729      18          3^6                  18
  1449     18          3^2 * 7 * 23         18
  1858     22          2 * 929              22
  1908     18          2^2 * 3^2 * 53       18
  2067     15          3 * 13 * 53          15
  2409     15          3 * 11 * 73          15
  2839     22          17 * 167             22
  4369     22          17 * 257             22
  4414     13          2 * 2207             13
  4464     18          2^4 * 3^2 * 31       18
  4880     20          2^4 * 5 * 61         20
  4960     19          2^5 * 5 * 31         19
  5458     22          2 * 2729             22
  5818     22          2 * 2909             22
  5854     22          2 * 2927             22
  6084     18          2^2 * 3^2 * 13^2     18
  6096     21          2^4 * 3 * 127        21
  6567     24          3 * 11 * 199         24
  6583     22          29 * 227             22
  6684     24          2^2 * 3 * 557        24
  6718     22          2 * 3359             22
  6760     19          2^3 * 5 * 13^2       19
  6880     22          2^5 * 5 * 43         22
  7068     21          2^2 * 3 * 19 * 31    21
  7078     22          2 * 3539             22
  7186     22          2 * 3593             22
  8158     22          2 * 4079             22
  8568     27          2^3 * 3^2 * 7 * 17   27
  8680     22          2^3 * 5 * 7 * 31     22
  8864     26          2^5 * 277            26
  8901     18          3^2 * 23 * 43        18
  9166     22          2 * 4583             22
  9414     18          2 * 3^2 * 523        18
  9849     30          3 * 7^2 * 67         30
  10669    22          47 * 227             22
  10786    22          2 * 5393             22
  10966    22          2 * 5483             22
  14458    22          2 * 7229             22
  14566    22          2 * 7283             22
  14958    27          2 * 3^3 * 277        27
  15646    22          2 * 7823             22
  15709    22          23 * 683             22
  15984    27          2^4 * 3^3 * 37       27
  16546    22          2 * 8273             22
  16866    27          2 * 3^2 * 937        27
  17496    27          2^3 * 3^7            27
  17664    24          2^8 * 3 * 23         24
  17718    24          2 * 3 * 2953         24
  17840    20          2^4 * 5 * 223        20
  18418    22          2 * 9209             22
  18454    22          2 * 9227             22
  19818    27          2 * 3^3 * 367        27
  20229    15          3 * 11 * 613         15
  20299    22          53 * 383             22
  22509    18          3^2 * 41 * 61        18
  26727    24          3 * 59 * 151         24
  33680    20          2^4 * 5 * 421        20
  33760    19          2^5 * 5 * 211        19
  33880    22          2^3 * 5 * 7 * 11^2   22

Friday, 22 May 2026

Alexander Grothendieck

This morning I read a Quanta Magazine article about a mathematician named Alexander Grothendieck titled How Alexander Grothendieck Revolutionized 20th Century Mathematics. I'd never heard of him. The article focuses on his mathematical contributions but says very little about his eccentric personal life. I asked Gemini the following:

Grothenddieck was a famous 20th century mathematician. Find out all you can about his personal life as opposed to his contributions to Mathematics. In particular what were his reasons for living as a recluse in the final years of his life. He fathered five children so presumably he turned his back on his family. 


Figure 1

Figure 1, taken from the Quanta Magazine article carries the following caption:
Grothendieck, seen here in 1954, was fascinated by hidden geometric structure. “If there is one thing in mathematics which fascinates me more than any other (and undoubtedly always has), it is neither ‘number’ nor ‘size,’ but invariably shape,” he wrote.

Here was Gemini's  response to my query:

You are entirely correct in your presumption. Despite fathering five children, Alexander Grothendieck was notoriously detached from his family and eventually abandoned those relationships completely. His colleague and biographer Pierre Cartier once noted that Grothendieck was "as absent a father to them as his own father was to him."

A Chaotic Family Life

Grothendieck's personal life was highly unstable, and his five children were born to three different women:

    • Serge: Born to his landlady in Nancy during his early university years. Grothendieck later unsuccessfully sued for custody.

    • Johanna (1959), Alexander (1961), and Mathieu (1965): Born to his wife, Mireille Dufour.

    • A fifth child: Born to Justine Skalba, with whom he lived in a radical pacifist commune in the early 1970s.

Ultimately, his intense, manic obsession with his work—and later his extreme political and mystical beliefs—left almost no room for traditional familial bonds. He eventually severed all ties with his children and his past.

Early Trauma and a Stateless Youth

To understand his eventual rejection of society, it is crucial to look at his deeply traumatic upbringing.

Born in Berlin in 1928, his parents were radical anarchists. His father, a Russian Jew, was handed over to the Nazis by the French Vichy government and murdered in Auschwitz. Alexander and his mother were interned in French refugee and concentration camps (such as Rieucros) during World War II, and he spent years hiding in the woods from authorities.

Grothendieck was technically stateless for most of his life, only taking French citizenship in 1971. This early exposure to the brutality of the state instilled in him a permanent, uncompromising distrust of institutions, authority, and eventually, the scientific establishment itself.


Grothendieck lived the final decades of his life
as a recluse in the French countryside.
This 2013 photo was taken a year before his death.

Reasons for His Final Retreat

Grothendieck did not become a recluse overnight. His withdrawal was a gradual, decades-long process fueled by profound moral convictions, deep disillusionment, and an increasingly fragile psychological state.

    • The 1970 Fracture: The major turning point occurred in 1970 when he discovered that his prestigious research home, the Institut des Hautes Études Scientifiques (IHÉS), received a small fraction of its funding from the French military. A strict pacifist, Grothendieck resigned immediately.

    • Radical Pacifism: He shifted his immense intellectual focus from mathematics to environmentalism and anti-militarism, founding a group called Survivre et Vivre (Survive and Live). He became convinced that mainstream science was inextricably linked to militarism and global destruction.

    • Rejection of the Establishment: By the 1980s, he felt completely alienated from his peers. In 1988, he famously refused the highly prestigious Crafoord Prize (and its $250,000 award). He wrote a scathing public letter to the Swedish Academy declaring that the scientific world had become ethically compromised and spiritually dead.

    • Descent into Mysticism: In his later years, his writings became highly focused on spirituality, the apocalypse, and mystical visions. He wrote thousands of pages of personal, philosophical reflections—most notably the massive Récoltes et Semailles (Reaping and Sowing)—which blended brilliant self-analysis with bitter grievances against his former friends and colleagues.

In 1991, he completely vanished from public life. He moved to Lasserre, a tiny village in the French Pyrenees, and legally demanded that all of his unpublished works be destroyed. For the last 23 years of his life, he refused visitors, ignored letters, and lived a fiercely ascetic, solitary existence until his death in 2014 at the age of 86.

The MacTutor has a quite detailed biography about Grothendieck. Within this biography, there are links to even more detailed information about him with this link being especially informative.

Wednesday, 20 May 2026

Dual Attractors

I've written about attractors, vortices, vorticals and captives in many earlier posts. In my nomenclature attractors can be prime/non-prime or odd/even:

  • a prime/non-prime attractor has sums of prime digits and non-prime digits that are equal
  • an odd/even attractor has sums of odd and even digits that are equal
An example of a prime/non-prime attractor would be 28330 where 2 + 3 + 3 = 8 + 0. Other numbers do not have this balance and under the recursion:

number --> number + sum of prime digits - sum of non-prime digits

some will be "attracted" to 28330, meaning that repeated application of the recursion will lead to the attractor. In the case of 28330, there are 19 such numbers (termed captives):
28327, 28331, 28332, 28333, 28334, 28335, 28336, 28337, 28338, 28339, 28340, 28341, 28342, 28343, 28344, 28345, 28346, 28348, 28349
An example of an odd/even attractor would be 29612 where 9 + 1 = 2 + 6 + 2. Other numbers again do not have this balance and under the recursion:

number --> number + sum of odd digits - sum of even digits

some will be "attracted" to 29612, meaning that repeated applications of the recursion will lead to the attractor. In the case of 29612, there are 20 such numbers (termed captives):
29517, 29537, 29559, 29571, 29583, 29585, 29587, 29590, 29591, 29592, 29594, 29596, 29598, 29605, 29610, 29611, 29613, 29614, 29616, 29618

Some attractors can be both prime/non-prime and odd/even and in the range up to 40000 there are 223 of them (permalink):

0, 112, 121, 211, 336, 358, 363, 385, 538, 583, 633, 835, 853, 1012, 1021, 1102, 1120, 1201, 1210, 2011, 2101, 2110, 3036, 3058, 3063, 3085, 3306, 3360, 3445, 3454, 3467, 3476, 3508, 3544, 3580, 3603, 3630, 3647, 3674, 3746, 3764, 3805, 3850, 4345, 4354, 4367, 4376, 4435, 4453, 4534, 4543, 4556, 4565, 4578, 4587, 4637, 4655, 4673, 4736, 4758, 4763, 4785, 4857, 4875, 5038, 5083, 5308, 5344, 5380, 5434, 5443, 5456, 5465, 5478, 5487, 5546, 5564, 5645, 5654, 5667, 5676, 5748, 5766, 5784, 5803, 5830, 5847, 5874, 6033, 6303, 6330, 6347, 6374, 6437, 6455, 6473, 6545, 6554, 6567, 6576, 6657, 6675, 6734, 6743, 6756, 6765, 6778, 6787, 6877, 7346, 7364, 7436, 7458, 7463, 7485, 7548, 7566, 7584, 7634, 7643, 7656, 7665, 7678, 7687, 7768, 7786, 7845, 7854, 7867, 7876, 8035, 8053, 8305, 8350, 8457, 8475, 8503, 8530, 8547, 8574, 8677, 8745, 8754, 8767, 8776, 10012, 10021, 10102, 10120, 10201, 10210, 11002, 11020, 11200, 12001, 12010, 12100, 20011, 20101, 20110, 21001, 21010, 21100, 30036, 30058, 30063, 30085, 30306, 30360, 30445, 30454, 30467, 30476, 30508, 30544, 30580, 30603, 30630, 30647, 30674, 30746, 30764, 30805, 30850, 33006, 33060, 33600, 34045, 34054, 34067, 34076, 34405, 34450, 34504, 34540, 34607, 34670, 34706, 34760, 35008, 35044, 35080, 35404, 35440, 35800, 36003, 36030, 36047, 36074, 36300, 36407, 36470, 36704, 36740, 37046, 37064, 37406, 37460, 37604, 37640, 38005, 38050, 38500

Let's take 37640 as an example:

  • it is a prime attractor since prime digits 3 + 7 = 6 + 4 + 0 (non-prime digits)

    It has 14 captives: 37612, 37615, 37617, 37623, 37627, 37632, 37633, 37641, 37642, 37643, 37644, 37646, 37648, 37649

  • it is an odd/even attractor since odd digits 3 + 7 = 6 + 4 + 0 (even digits)

    It has 11 captives: 37611, 37617, 37619, 37629, 37633, 37641, 37642, 37643, 37644, 37646, 37648

Of course the order of digits makes no difference and so many of these 223 numbers are just permutations of another's digits and 0's can be added anywhere because they do not affect the sum. Take 358 as an example. Permutations of its digits with or without 0 added include 385, 538, 583, 835, 853, 3058, 3085, 3508, 3580, 3805, 3850 etc.

In fact if we strip out the zeroes and put the digits in ascending order then the above list of 223 reduces to merely 112, 336, 358, 3445, 3467, 4556, 4578, 5667, 6778.

Tuesday, 19 May 2026

Conway's Constant


John Conway 1937 - 2020
biographical link

Having watched this
YouTube video on Conway' Constant, I was confused and asked Gemini the following question:

Can you explain Conway's Constant as it arises from the "look and say" sequence. In particular, I'm finding it hard to understand the connection with the irreducible polynomial of degree 71 and the idea of the 94 atoms that are named after the chemical elements. I'd like a comprehensive overview that ties everything together.

Back in February of 2017, I'd created a blog post titled Look and Say Sequence in which I'd mentioned this polynomial but I hadn't delved into it in any depth. Gemini's report is quite comprehensive and is included below. I don't pretend to understand all of what's included but nonetheless it's very interesting.

The Cosmological Theorem and Audioactive Decay: An Exhaustive Analysis of Conway’s Constant, the Look-and-Say Sequence, and the 94-Element Finite-State Automaton


Introduction

Within the study of deterministic integer sequences and formal language theory, the "look-and-say" sequence presents a uniquely profound case study. Originally introduced to the broader mathematical community by John Horton Conway—after being presented with the concept by a student at a party—the sequence appears at first glance to be a recreational puzzle governed by elementary rules. However, beneath its seemingly chaotic and rapidly expanding numeric surface lies a rigid, finite-state topology governed by linear algebra, graph theory, and automata mechanics.

The sequence is generated iteratively through a process analogous to run-length encoding. Beginning with a single seed digit, typically "1", each subsequent term is generated by reciting the contiguous blocks of identical digits in the previous term. The sequence proceeds as follows: the first term "1" is read aloud as "one 1", which translates mathematically into the second term, "11". The term "11" consists of two 1s, leading to the third term, "21". The sequence thus unfolds as 1, 11, 21, 1211, 111221, 312211, 13112221, and so forth, ad infinitum.

While the sequence ostensibly possesses the capacity for unbounded structural variation, Conway’s rigorous formal analysis revealed that it is governed by an underlying set of strictly deterministic decay mechanisms that mirror radioactive fission. Through the iterative application of what Conway termed the "audioactive operator," any string of integers systematically decomposes into a finite, universally stable set of fundamental non-interacting sub-strings.

This discovery culminated in Conway's Cosmological Theorem, a seminal result which proves that any arbitrary starting string will ultimately decay into a compound formed from precisely 94 fundamental atomic "elements". These elements are named in homage to the chemical periodic table, spanning the 92 primordial elements from Hydrogen to Uranium, alongside two "transuranic" families—Plutonium and Neptunium—to account for digits greater than 3.

The asymptotic growth rate of the string's digit length is strictly dictated by a $92 \times 92$ transition matrix mapping the evolutionary pathways of the common elements. The dominant eigenvalue of this matrix represents a constant multiplicative growth factor known as Conway's Constant, denoted as $\lambda \approx 1.303577269$. Crucially, while the transition matrix dictates a characteristic polynomial of degree 92, the constant $\lambda$ is formally defined as the unique positive real root of a much smaller, irreducible polynomial of degree 71, which emerges after factoring out degenerate cyclic subsystems within the decay matrix.

This report provides an exhaustive, granular analysis of the look-and-say sequence, detailing the mechanics of the audioactive operator, the complete taxonomy and evolutionary transitions of the 94 atomic elements, the structural sparseness of the transition matrix, the rigorous mathematical derivations underlying the degree-71 polynomial, and the modern applications of finite-state automata in verifying the Cosmological Theorem.

The Mathematical Mechanics of Audioactive Decay

To formally evaluate the look-and-say sequence, it must be detached from linguistic recitation and formalized as a string manipulation operator. The process is driven by the audioactive operator, denoted herein as $\mathcal{A}$, which acts upon finite sequences of positive integers.

Let a string $S$ be represented by its maximal contiguous blocks of identical digits. If we define $S = d_1^{e_1} d_2^{e_2} \dots d_n^{e_n}$, where $d_i$ represents a specific numerical digit and $e_i$ denotes the exact continuous frequency of that digit (such that $d_i \neq d_{i+1}$ for all valid $1 \le i < n$), then the application of the audioactive operator yields the daughter string:$$\mathcal{A}(S) = e_1 d_1 e_2 d_2 \dots e_n d_n$$Applying the operator iteratively generates the descendent sequences of the initial seed $S$, denoted as $\mathcal{A}^k(S)$ for $k \in \mathbb{N}$. A sequence that is identical to $\mathcal{A}^k(S)$ for some seed $S$ and an integer $k$ is formally referred to as a "$k$-day-old" string.

The Bounded Digit Phenomenon

A profound structural limitation of the operator $\mathcal{A}$ is that, unless a digit $d \ge 4$ is deliberately introduced into the initial seed $S$, the descendant strings will indefinitely consist entirely of the digits 1, 2, and 3. It is mathematically impossible for a contiguous block of four identical digits to emerge naturally from the standard audioactive derivation.

To demonstrate this, consider the conditions required for a "4" to appear in $\mathcal{A}^k(S)$ without existing in $S$. The operator would need to evaluate a sub-string in $\mathcal{A}^{k-1}(S)$ consisting of four identical adjacent digits, such as "1111". However, for "1111" to exist in $\mathcal{A}^{k-1}(S)$, the preceding generation $\mathcal{A}^{k-2}(S)$ would need to contain a segment that reads as "one 1, one 1". By the fundamental definition of the maximal grouping property inherent to $\mathcal{A}$, the substring "one 1, one 1" would have been immediately condensed into "two 1s" (resulting in the string "21") during the transition from $k-2$ to $k-1$.

Because of this strict condensation rule, any sequence initiated with a seed consisting solely of 1s, 2s, and 3s is definitively closed over the alphabet $\{1, 2, 3\}$.

String Splitting and the Definition of Atoms

The mathematical viability of Conway's analysis hinges on the discovery that long strings do not behave as single, highly entangled macroscopic entities, but rather fragment into completely independent microscopic components. This phenomenon is known as "splitting".

A string $S$ is mathematically defined as splitting into a left contiguous sub-string $L$ and a right contiguous sub-string $R$ (denoted $S = L \cdot R$) if the evolutionary descendants of $L$ and $R$ never cross-interfere at their boundary. Formally, for all $k \ge 0$, the $k^{th}$ derivation of the concatenated string must exactly equal the concatenation of the $k^{th}$ derivations of the individual sub-strings:
$$\mathcal{A}^k(L \cdot R) = \mathcal{A}^k(L) \cdot \mathcal{A}^k(R)$$When this splitting property holds, the evolution of $L$ is completely abstracted from the evolution of $R$. If a valid, non-empty string cannot be split any further into smaller, independently evolving strings, it is classified as an "atom" or an "element". Consequently, every non-empty look-and-say string can be uniquely factored into an ordered concatenation of these indivisible atoms, which are then free to evolve along their own deterministic trajectories.

The Taxonomy of the 92 Common Elements

Through rigorous manual computation and later verified by exhaustive computational searches, Conway identified that there are exactly 92 distinct atoms composed strictly of the digits 1, 2, and 3 that dominate the sequence. These atoms are fundamentally stable in their evolutionary logic; when the operator $\mathcal{A}$ is applied to a common element, the resulting daughter string will invariably consist solely of one or more of these same 92 elements.

In a brilliant metaphor that has defined the nomenclature of the field, Conway named these 92 elements in direct correspondence with the periodic table of chemical elements, mapping them from Hydrogen (atomic number 1) to Uranium (atomic number 92).

The interaction and decay of these elements are highly structured. Rather than randomly converting into any other element, they follow a strict, uni-directional decay hierarchy. With the exception of certain closed cyclic transitions, heavier elements consistently decay into lighter compounds.

The Complete Periodic Table of Audioactive Decay

The following table presents the exhaustive enumeration of all 92 common look-and-say elements, outlining their exact digit string representations and their immediate evolutionary decay products under a single application of the audioactive operator $\mathcal{A}$. The ordering is presented in reverse topological order, starting from Uranium, demonstrating the decay cascade that ultimately terminates at Hydrogen.

Atomic Number Element Symbol String Representation Decay Products / Evolution
92U (Uranium)3Pa
91Pa (Protactinium)13Th
90Th (Thorium)1113Ac
89Ac (Actinium)3113Ra
88Ra (Radium)132113Fr
87Fr (Francium)1113122113Rn
86Rn (Radon)311311222113Ho, At
85At (Astatine)1322113Po
84Po (Polonium)1113222113Bi
83Bi (Bismuth)3113322113Pm, Pb
82Pb (Lead)123222113Tl
81Tl (Thallium)111213322113Hg
80Hg (Mercury)31121123222113Au
79Au (Gold)132112211213322113Pt
78Pt (Platinum)111312212221121123222113Ir
77Ir (Iridium)3113112211322112211213322113Os
76Os (Osmium)1321132122211322212221121123222113Re
75Re (Rhenium)111312211312113221133211322112211213322113Ge, Ca, W
74W (Tungsten)312211322212221121123222113Ta
73Ta (Tantalum)13112221133211322112211213322113Hf, Pa, H, Ca, W
72Hf (Hafnium)11132Lu
71Lu (Lutetium)311312Yb
70Yb (Ytterbium)1321131112Tm
69Tm (Thulium)11131221133112Er, Ca, Co
68Er (Erbium)311311222Ho, Pm
67Ho (Holmium)1321132Dy
66Dy (Dysprosium)111312211312Tb
65Tb (Terbium)3113112221131112Ho, Gd
64Gd (Gadolinium)13221133112Eu, Ca, Co
63Eu (Europium)1113222Sm
62Sm (Samarium)311332Pm, Ca, Zn
61Pm (Promethium)132Nd
60Nd (Neodymium)111312Pr
59Pr (Praseodymium)31131112Ce
58Ce (Cerium)1321133112La, H, Ca, Co
57La (Lanthanum)11131Ba
56Ba (Barium)311311Cs
55Cs (Caesium)13211321Xe
54Xe (Xenon)11131221131211I
53I (Iodine)311311222113111221Ho, Te
52Te (Tellurium)1322113312211Eu, Ca, Sb
51Sb (Antimony)3112221Pm, Sn
50Sn (Tin)13211In
49In (Indium)11131221Cd
48Cd (Cadmium)3113112211Ag
47Ag (Silver)132113212221Pd
46Pd (Palladium)111312211312113211Rh
45Rh (Rhodium)311311222113111221131221Ho, Ru
44Ru (Ruthenium)132211331222113112211Eu, Ca, Tc
43Tc (Technetium)311322113212221Mo
42Mo (Molybdenum)13211322211312113211Nb
41Nb (Niobium)1113122113322113111221131221Er, Zr
40Zr (Zirconium)12322211331222113112211Y, H, Ca, Tc
39Y (Yttrium)1112133Sr, U
38Sr (Strontium)3112112Rb
37Rb (Rubidium)1321122112Kr
36Kr (Krypton)11131221222112Br
35Br (Bromine)3113112211322112Se
34Se (Selenium)13211321222113222112As
33As (Arsenic)11131221131211322113322112Ge, Na
32Ge (Germanium)31131122211311122113222Ho, Ga
31Ga (Gallium)13221133122211332Eu, Ca, Ac, H, Ca, Zn
30Zn (Zinc)312Cu
29Cu (Copper)131112Ni
28Ni (Nickel)11133112Zn, Co
27Co (Cobalt)32112Fe
26Fe (Iron)13122112Mn
25Mn (Manganese)111311222112Cr, Si
24Cr (Chromium)31132V
23V (Vanadium)13211312Ti
22Ti (Titanium)11131221131112Sc
21Sc (Scandium)3113112221133112Ho, Pa, H, Ca, Co
20Ca (Calcium)12K
19K (Potassium)1112Ar
18Ar (Argon)3112Cl
17Cl (Chlorine)132112S
16S (Sulfur)1113122112P
15P (Phosphorus)311311222112Ho, Si
14Si (Silicon)1322112Al
13Al (Aluminium)1113222112Mg
12Mg (Magnesium)3113322112Pm, Na
11Na (Sodium)123222112Ne
10Ne (Neon)111213322112F
9F (Fluorine)31121123222112O
8O (Oxygen)132112211213322112N
7N (Nitrogen)111312212221121123222112C
6C (Carbon)3113112211322112211213322112B
5B (Boron)1321132122211322212221121123222112Be
4Be (Beryllium)111312211312113221133211322112211213322112Ge, Ca, Li
3Li (Lithium)312211322212221121123222112He
2He (Helium)13112221133211322112211213322112Hf, Pa, H, Ca, Li
1H (Hydrogen)22H (stable)

Topological Properties of the Decay Graph

The interactions documented in the table above map out a highly asymmetric, deterministic directed acyclic graph (DAG) with localized periodic loops. The most profound structural observation is the universal convergence toward Hydrogen (22). Hydrogen represents the absolute ground state of the sequence; when evaluated by the audioactive operator $\mathcal{A}$, the string "22" is read as "two 2s", yielding "22". It is perfectly stable, immune to macroscopic expansion or structural alteration.

If one traces the cascade starting from Uranium (string 3), the sequence undergoes exactly 91 distinct decay steps before producing an isolated, stable Hydrogen atom at the end of the chain. However, Hydrogen can manifest internally much earlier. After just 14 evolutionary steps from Uranium, the sequence produces a complex compound containing 15 discrete elements—ranging from Dysprosium down to Platinum—within which a Hydrogen atom natively appears.

Another strict mathematical boundary in this system is the limitation on atomic recombination. Two adjacent elements cannot be arbitrarily merged without entirely disrupting their evolutionary pathways. For instance, combining Uranium (3) with Calcium (12) forms the string 312. Instead of decaying independently as U and Ca, the combined string 312 behaves identically to Zinc, decaying into Copper (131112). This non-linear interference proves that the splitting theorem strictly applies only at the precise cleavage boundaries of the canonical 92 elements.

Furthermore, while Conway's numbering (U=92 down to H=1) is the classic topological sort, it is not mathematically unique. Structural analysis reveals that there are exactly seven possible complete topological orderings of these 92 elements that preserve the rule that an element must generally decay into elements of a lower atomic number. Alternative valid sequences restructure the middle block of lanthanides and transition metals—such as swapping the priority of the Ho-Gd, Eu-Sm, and Pm-Y decay clusters—but all orderings invariably lock U at the top and H at the absolute bottom.

The Transuranic Elements and the 94-State Automaton

While the 92 primordial elements completely characterize any sequence containing only the digits 1, 2, and 3, a generalized theorem must account for all possible integer seeds. If an individual were to seed the look-and-say sequence with a digit $n \ge 4$, the behavior of the operator $\mathcal{A}$ initially introduces unfamiliar strings.

To mathematically sequester these anomalies, Conway proved that any anomalous digit $d \ge 4$ is rapidly pushed toward the end of an evolving sub-string. Over successive iterations, these high digits become permanently trapped at the terminal position of a highly specific prefix string.

Conway categorized these high-digit sinks as the "transuranic elements," naming them after Plutonium (Pu) and Neptunium (Np). The naming convention borrows heavily from nuclear chemistry, reflecting that these atoms do not occur "naturally" in sequences descending from 1, 2, or 3, just as Pu and Np do not generally occur in significant natural terrestrial quantities but are artificial by-products of nuclear reactions (e.g., Np-237 and Pu-238).

For every integer $n \ge 4$, an isotope of Plutonium and an isotope of Neptunium is defined by a specific constant prefix, followed by the variable digit $n$:

  • Isotope of Plutonium ($n$Pu): 31221132221222112112322211$n$
  • Isotope of Neptunium ($n$Np): 1311222113321132211221121332211$n$

These two families operate in a perfectly closed loop. When the audioactive operator is applied, a Plutonium isotope decays into a Neptunium isotope, and a Neptunium isotope decays directly back into a Plutonium isotope. During these transformations, the prefixes continuously shed fragments that immediately resolve into standard common elements (like Hf, Pa, H, and Ca), leaving the trapped digit $n$ endlessly oscillating between the Pu and Np structural states.

Because every possible isotope $n$ behaves identically concerning the topology of the decay graph, automata theory abstracts this infinite family of digits into just two functional states. Therefore, the complete finite-state machine (FSM) required to map the evolution of any arbitrary look-and-say sequence requires exactly 94 distinct states: the 92 primordial elements plus the two transuranic element classes.

The Cosmological Theorem

The synthesis of these elemental mechanics is formalized as Conway's Cosmological Theorem.

The theorem posits that every arbitrary sequence of positive integers has a finite "longevity" before it loses all chaotic macroscopic properties. Formally, it asserts that there exists an integer threshold $N$ such that, after $N$ successive applications of the audioactive operator $\mathcal{A}$, the resulting string will irreversibly split into a concatenation of the 94 fundamental elements. From the $N^{th}$ iteration onward, the string is no longer a single complex entity but a compound of chemically independent audioactive atoms.

While Conway and Richard Parker originally provided a proof for this theorem, the manuscript was famously lost. Mike Guy subsequently established an upper bound, proving that any arbitrary sequence will fully decay into atoms in no more than 24 iterations, or $N=24$ "days". The absolute maximum longevity across all possible string formulations is thus defined as the "cosmological constant," exactly 24.

A rigorous, verifiable proof was later reconstructed by Shalosh B. Ekhad and Doron Zeilberger. They developed a complex Maple program to map the decay properties of the sequence. Ekhad and Zeilberger significantly reduced the computational complexity of the proof by restricting their analysis. Because any digits greater than 3 migrate to the terminal end of an atom by day 2 (ultimately forming transuranic elements), the problem space can be reduced to analyzing strings constructed solely from $\{1, 2, 3\}$. By proving that all permutations within the $\{1, 2, 3\}$ alphabet achieve atomic stability within a maximum longevity of 24, they established that an arbitrary string containing any digits whatsoever must achieve stability within $24 + 2 = 26$ days, later tightened back to exactly 24. To exhaust the infinite space of strings, they relied on "isotopic classes"—a mapping of basic state bijection sets to track topological transformations, allowing the computer to iterate through a finite representation of all sequence behaviors.

Recent developments in automata theory have corroborated the Cosmological Theorem using finite-state machine minimization techniques. By treating the generation rule as a deterministic transducer mapping integer sequences, algorithms can compose and minimize the states to verify that the 94 specific elemental states are necessary and perfectly sufficient for closure; there are no edge cases or rogue sequences that can escape the 94-element boundary.

The $92 \times 92$ Transition Matrix and Linear Dynamics

Once a sequence passes the cosmological horizon of $N=24$, its future evolution is strictly deterministic and perfectly linear. Because the 92 common elements split and evolve independently, the entire future state of the sequence can be modeled as a discrete-time dynamical system governed by a constant $92 \times 92$ transition matrix $T$.

Let the state of the sequence at iteration $k$ be defined by a column vector $v_k \in \mathbb{R}^{92}$, where the $i^{th}$ entry corresponds to the exact quantity of the $i^{th}$ atom present in the sequence. The evolution to the next generation $k+1$ is calculated via matrix multiplication:$$v_{k+1} = T v_k$$The matrix $T$ is constructed directly from the periodic table of decay transitions. Each column represents an element, and the rows represent the products it generates. For example, element 28 (Nickel) decays into element 30 (Zinc) and element 27 (Cobalt). Thus, the $28^{th}$ column of matrix $T$ contains a $1$ in the $30^{th}$ and $27^{th}$ rows, and $0$ in all others.

Matrix Structure and Dimensional Sparsity

An analysis of the matrix $T$ reveals severe structural asymmetry. It is an integer matrix containing only non-negative entries—overwhelmingly 0s, with scattered 1s and 2s representing stoichiometric quantities.

Because elements predominantly decay into lighter elements, following a thermodynamic arrow of increasing Boltzmannian entropy, the matrix naturally tends toward a block-triangular or lower-triangular structure. Specifically, the lower-triangular portion of the matrix is determined to be approximately 8.7 times denser than the upper-triangular portion, reflecting the rarity of elements "fusing" upward into heavier compounds.

This extreme sparsity and the presence of numerous rows containing near-identical entries allow mathematical simplifications via integer relations. By identifying components that evolve synchronously, the matrix can be collapsed, eliminating redundant rows without necessitating floating-point approximation. These variables are pivotal in reducing the computational intensity of extracting the system's eigenvalues.

The Perron-Frobenius Theorem and Asymptotic Growth

To understand the macro-scale growth of the string's length, one must evaluate the eigenvalues of $T$. Because $T$ is a non-negative matrix, the Perron-Frobenius theorem dictates that there exists a unique, strictly positive, real eigenvalue—often called the spectral radius or maximal eigenvalue $\lambda$—that fundamentally dominates the system's asymptotic behavior.

For any state vector $v_k$, as $k \to \infty$, the ratio of the total elements in successive vectors perfectly converges to this spectral radius. If $L_n$ represents the total digit length of the sequence at the $n^{th}$ generation, its length asymptotically scales according to $L_n \approx c \lambda^n$.

Crucially, the presence of the transuranic elements (Plutonium and Neptunium) does not influence this dominant growth rate. The matrix block managing the oscillating Pu $\leftrightarrow$ Np reactions produces eigenvalues of precisely $\pm 1$ modulo the core subspace. Because the absolute modulus of the transuranic eigenvalues ($|\pm 1| = 1$) is strictly less than the spectral radius $\lambda \approx 1.303$, their proportional influence decays geometrically. Consequently, as the main sequence explodes in length at a rate of 30.3% per step, the relative abundance of transuranic elements converges asymptotically to zero.

Derivation of the Degree-71 Polynomial

The maximal eigenvalue $\lambda$ is famously known as Conway's Constant:$$\lambda \approx 1.303577269 \dots $$By definition, the eigenvalues of a matrix are the roots of its characteristic polynomial, calculated as $\det(\lambda I - T) = 0$. Because $T$ is a $92 \times 92$ transition matrix, the characteristic polynomial $P_{92}(\lambda)$ inherently possesses a degree of exactly 92.

However, Conway's Constant is heavily documented across mathematical literature as the root of an irreducible polynomial of degree 71, not 92.

This structural discrepancy is reconciled through algebraic factorization. The characteristic polynomial of degree 92 is highly reducible over the field of rational numbers due to the macroscopic topological properties of the transition matrix. When $T$ is evaluated into its rational canonical form, many of the subsystems representing the finite decay paths resolve into factors that map entirely separate, non-exponential dynamics.

Specifically, the characteristic polynomial cleanly factors as:$$P_{92}(\lambda) = \lambda^{28} (\lambda - 1) (\lambda + 1) (\lambda^2 + 1) (\lambda^4 + 1) (\lambda^8 + 1) \cdot p_{71}(\lambda)$$Each factored term carries specific structural significance within the automaton:

  • The $\lambda^{28}$ term: The algebraic multiplicity of the eigenvalue 0 is 28. This massive nilpotent root cluster stems directly from the block-triangular structure and sparsity of $T$. It indicates that 28 dimensional degrees of freedom within the vector space correspond to "dead-end" decay pathways—elements that rapidly transition toward the ground state (Hydrogen) without looping back or contributing to the long-term exponential multiplication of the string.

  • The Cyclotomic Factors: The terms $(\lambda \pm 1), (\lambda^2 + 1), (\lambda^4 + 1),$ and $(\lambda^8 + 1)$ are cyclotomic polynomials. Their roots are complex roots of unity (e.g., $i, -i$). Geometrically, these correspond to strictly periodic, cyclic loops within the elemental decay graph. They describe subsets of elements that endlessly oscillate in cycles of length 1, 2, 4, or 8. Because the absolute value of all roots of unity is 1, these cyclic loops do not dictate geometric expansion, and their relative impact on the string length washes out to zero against the primary exponential growth.


The Irreducible Factor $p_{71}(\lambda)$

After dividing out the nilpotent elements and the roots of unity, the residual expression is an irreducible polynomial of degree 71 over the integers $\mathbb{Z}$. The roots of this 71-degree polynomial hold the true expansive eigen-dynamics of the transition matrix.

The full polynomial $p_{71}(x)$ is presented as follows:

$ x^{71} - x^{69} - 2x^{68} - x^{67} + 2x^{66} + 2x^{65} + x^{64} - x^{63} - x^{62} - x^{61}$

$ - x^{60} - x^{59}+ 2x^{58} + 5x^{57}+ 3x^{56} - 2x^{55} - 10x^{54} - 3x^{53} - 2x^{52} + 6x^{51}$

$ + 6x^{50} + x^{49} + 9x^{48}- 3x^{47} - 7x^{46} - 8x^{45} - 8x^{44} + 10x^{43}+ 6x^{42} + 8x^{41}$

$ - 5x^{40} - 12x^{39} + 7x^{38} - 7x^{37}+ 7x^{36} + x^{35} - 3x^{34} + 10x^{33} + x^{32} - 6x^{31}$ 

$- 2x^{30} - 10x^{29} - 3x^{28} + 2x^{27} + 9x^{26}- 3x^{25} + 14x^{24} - 8x^{23} - 7x^{21} + 9x^{20}$ 

$+ 3x^{19} - 4x^{18} - 10x^{17} - 7x^{16} + 12x^{15}+ 7x^{14} + 2x^{13} - 12x^{12} - 4x^{11} - 2x^{10} $ 

$+ 5x^9 + x^7 - 7x^6 + 7x^5 - 4x^4 + 12x^3 - 6x^2 + 3x - 6 = 0 $

According to the Perron-Frobenius theorem, this irreducible polynomial guarantees exactly one unique positive real root. Evaluating this root yields Conway's Constant, $\lambda \approx 1.303577269 \dots $, meaning the look-and-say string grows by roughly 30.3% with each iteration.

The manifestation of such a massive, un-simplifiable polynomial from an elementary numeric puzzle is highly unusual. Within combinatorial mathematics, the emergence of naturally occurring algebraic numbers with such high degrees is rare. Other comparable phenomena typically arise only in the deep structural onset of chaotic regimes, such as the 7-cycle onset of the logistic map (degree 114) or specific random matrix models.

Eigenvectors and Asymptotic Elemental Abundances

A direct corollary of deriving the maximal eigenvalue $\lambda$ is the evaluation of its corresponding primary eigenvector. In linear algebra, the primary eigenvector maps the stable, steady-state proportions of the system. As the sequence extends toward infinity, the specific initial seed becomes statistically irrelevant; the relative ratio of the 92 constituent atoms converges absolutely to the coordinates of this primary eigenvector.

Because the vector encapsulates the stoichiometric balance of the elements under continuous fission, it reveals massive disparities in atomic distribution. Hydrogen (22) acts as the ultimate structural sink. As the heaviest elements cascade downward, their descendent paths universally terminate at Hydrogen, causing it to accumulate at a tremendous rate.

Calculations based on the transition matrix eigenvector dictate that Hydrogen is the most abundant element by an overwhelming margin. Out of every 1,000,000 atoms present in a mature sequence, approximately 91,790 of them will be Hydrogen. Conversely, elements that reside on sparse, narrow branches of the DAG without cyclic regeneration are remarkably scarce. Arsenic, for instance, represents the rarest element in the network, appearing on average only 27 times per million atoms. Thus, Conway's matrix modeling provides not just the gross length of the sequence, but a perfect probabilistic model of its microscopic composition over infinite iterations.

Cross-Base Generalizations and Formal Language Invariance

While Conway’s 94-element cosmological framework and the degree-71 polynomial are strictly tethered to the base-10 numerical interpretation of the look-and-say operator, the underlying phenomenon of audioactive decay is invariant across bases. The spontaneous collapse of iterative sequence generation into closed, stable, finite-state decay networks is a fundamental property of run-length encoding recursion.

Evaluating the sequence using base-3 (ternary) representations restricts the alphabet, significantly compressing the necessary states. Analysis has shown that a ternary look-and-say sequence yields a total of only 24 distinct, irreducible elements, generating a completely different transition matrix and a correspondingly smaller polynomial.

Further constraints down to base-2 (binary) variants reduce the "periodic table" to a mere 10 elementary sub-strings. Regardless of the base chosen (be it base-3, base-4, or standard decimal), as long as the base exceeds the maximum contiguous block size generated by the sequence rules, an equivalent transition matrix exists. The specific spectral radius $\lambda$ diverges across bases—for instance, the ternary $\lambda$ is different from the base-10 Conway's constant—but the existence of an irreducible transition matrix, an isolated set of atomic states, and a dominant real growth factor remains mathematically universal.

Conclusion

The exploration of Conway’s look-and-say sequence reveals a brilliant intersection between combinatorial puzzles and deep linear dynamical systems. What begins as an elementary linguistic recitation mechanism inherently constrains itself through the rigid logic of run-length encoding. The sequence cannot expand randomly; it is subjected to immediate microscopic fission, splitting into chemically independent sub-strings.

Conway’s Cosmological Theorem elegantly maps this phenomenon, proving that any arbitrary sequence inevitably collapses into a bounded set of 94 fundamental elemental states within 24 iterations. By abstracting out the anomalies introduced by high-value digits via the oscillating transuranic Plutonium and Neptunium loops, the remaining 92 primordial elements form a unified, completely predictable linear network.

The asymptotic growth rate of the entire system is perfectly encapsulated by the transition matrix of these 92 elements. While the structural sparsity and dead-end pathways of the elemental decay hierarchy produce a 92-degree characteristic polynomial burdened with nilpotent roots and cyclotomic loops, the geometric core of the expansion is housed entirely within an irreducible, 71-degree factor.

Conway's Constant ($\lambda \approx 1.303577$) - the unique positive real root of this 71-degree polynomial - is therefore not merely a statistical growth rate. It is the absolute mathematical limit dictated by the topology of the 94-element state machine, governing both the exponential expansion of the string and the steady-state eigenvector abundances of its atomic components. The look-and-say sequence thus transcends its origins, standing as a premier demonstration of how simple, deterministic recursive operators spontaneously architect complex, irreducible finite-state universes.

Monday, 18 May 2026

Base 10 Primes in Higher Number Bases

The thought struck me as to what primes in base 10 remain prime when the digits stay the same but the number base increases to 11, 12, 13 etc. I got Gemini to investigate and it came up with useful summary and an impressive interactive tool for investigation:

To analyze this integer sequence mathematically, we can define the transformation as evaluating a polynomial.

Let a base-10 prime \( p \) have the decimal representation \( d_k d_{k-1} \dots d_1 d_0 \). The value of \( p \) is given by:

\[ p = \sum_{i=0}^{k} d_i 10^i \]

When we take these same digits and interpret them in a higher base \( b \) (where \( 11 \le b \le 36 \)), we are evaluating the new integer \( P_b \):

\[ P_b = \sum_{i=0}^{k} d_i b^i \]

The task is to find all instances where both \( p \) and \( P_b \) are prime. When we run this analysis across different bases, distinct number-theoretic patterns emerge, particularly regarding parity and divisibility.

The Parity Sieve for Odd Bases

The parity of the new number \( P_b \) depends entirely on whether the target base \( b \) is odd or even.

If the target base \( b \) is odd (e.g., base 11, 13, 15), then \( b \equiv 1 \pmod 2 \). Consequently, the modulo-2 value of the new number collapses to the sum of its digits:

\[ P_b \equiv \sum_{i=0}^{k} d_i \pmod 2 \]

This creates a massive sieve: if the sum of the digits of the original prime \( p \) is even, \( P_b \) will inevitably be even. Since \( P_b > 2 \) for all target primes in these higher bases, an even \( P_b \) is strictly composite. Therefore, odd bases yield a significantly sparser sequence of primes.

The Density in Even Bases

If the target base \( b \) is even (like the default \( b=16 \)), then \( b \equiv 0 \pmod 2 \). In this scenario, all terms multiplied by \( b \) are even, meaning the parity of \( P_b \) relies solely on the final digit \( d_0 \):

\[ P_b \equiv d_0 \pmod 2 \]

Because \( p \) is prime in base-10, its final digit \( d_0 \) must be odd (1, 3, 7, or 9) with the sole exception of \( p=2 \). Therefore, \( P_b \) will always be odd in an even base. Because they bypass the digit-sum parity trap, even bases like 16 retain a much higher density of prime numbers.

Small Examples in Base 16

For \( b=16 \), examining the first few base-10 primes reveals the retention rate:

  • 11: \( 1(16) + 1 = 17 \) (Prime)
  • 13: \( 1(16) + 3 = 19 \) (Prime)
  • 17: \( 1(16) + 7 = 23 \) (Prime)
  • 19: \( 1(16) + 9 = 25 \) (Composite, \( 5 \times 5 \))
  • 23: \( 2(16) + 3 = 35 \) (Composite, \( 5 \times 7 \))
  • 29: \( 2(16) + 9 = 41 \) (Prime)

To thoroughly investigate the sequence up to 40,000 across any base from 11 to 36 without relying on a static, truncated list, the interactive tool below is designed to compute the results dynamically. It handles the base conversions and primality testing locally within your browser.

Total Primes Found: 0
Index Base 10 Prime Value in Target Base

Highly Primeable Numbers

A composite numbers is primeable if it can be made prime by changing a single digit. If it cannot, then it is said to be unprimeable. What struck me about the number associated with my diurnal age today (28169) is how many ways (10) in which it can be made prime.

28169 is NOT unprimeable. It can be made prime with the following changes (permalink):

- Changing the '2' at position 1 (from the left) to '1' yields 18169
- Changing the '2' at position 1 (from the left) to '5' yields 58169
- Changing the '2' at position 1 (from the left) to '8' yields 88169
- Changing the '8' at position 2 (from the left) to '1' yields 21169
- Changing the '8' at position 2 (from the left) to '4' yields 24169
- Changing the '8' at position 2 (from the left) to '5' yields 25169
- Changing the '1' at position 3 (from the left) to '0' yields 28069
- Changing the '1' at position 3 (from the left) to '6' yields 28669
- Changing the '6' at position 4 (from the left) to '0' yields 28109
- Changing the '9' at position 5 (from the left) to '3' yields 28163

This got me thinking about highly primeable numbers and what numbers are record breakers by setting records for the number of ways in which they can be made prime. I got Gemini to write a program to investigate this and here is what it came up with in the range up to 100000 (permalink):

Record-Breaking Primeable Numbers
----------------------------------------
Number          | Ways to Make Prime
----------------------------------------
4               | 4
21              | 7
33              | 8
111             | 10
133             | 11
177             | 13
357             | 14
1001            | 15
4221            | 16
10759           | 17
11487           | 18
42189           | 20
----------------------------------------

Here is the list of numbers: 4, 21, 33, 111, 133, 177, 357, 1001, 4221, 10759, 11487, 42189.

So we see that 28169, though highly primeable, is NOT a record breaker.

Let's look at the 20 ways in which 42189 can be made prime:

42189 is NOT unprimeable. It can be made prime with the following changes (permalink):
- Changing the '4' at position 1 (from the left) to '2' yields 22189 - Changing the '4' at position 1 (from the left) to '3' yields 32189 - Changing the '4' at position 1 (from the left) to '5' yields 52189 - Changing the '4' at position 1 (from the left) to '6' yields 62189 - Changing the '4' at position 1 (from the left) to '8' yields 82189 - Changing the '4' at position 1 (from the left) to '9' yields 92189 - Changing the '2' at position 2 (from the left) to '0' yields 40189 - Changing the '2' at position 2 (from the left) to '1' yields 41189 - Changing the '2' at position 2 (from the left) to '3' yields 43189 - Changing the '2' at position 2 (from the left) to '4' yields 44189 - Changing the '2' at position 2 (from the left) to '7' yields 47189 - Changing the '1' at position 3 (from the left) to '0' yields 42089 - Changing the '1' at position 3 (from the left) to '5' yields 42589 - Changing the '1' at position 3 (from the left) to '6' yields 42689 - Changing the '1' at position 3 (from the left) to '9' yields 42989 - Changing the '8' at position 4 (from the left) to '3' yields 42139 - Changing the '8' at position 4 (from the left) to '6' yields 42169 - Changing the '8' at position 4 (from the left) to '7' yields 42179 - Changing the '9' at position 5 (from the left) to '1' yields 42181 - Changing the '9' at position 5 (from the left) to '7' yields 42187

While the above table shows record breakers, there are other numbers that equal existing records but do NOT set those records themselves. The following table shows these numbers (permalink) in the range up to 100,000.

Numbers Equaling an Existing Record
----------------------------------------
Number          | Ways to Make Prime
----------------------------------------
6               | 4
8               | 4
9               | 4
10              | 4
12              | 4
14              | 4
15              | 4
16              | 4
18              | 4
27              | 7
49              | 8
63              | 8
77              | 8
119             | 10
147             | 11
153             | 11
1011            | 15
1099            | 15
1209            | 15
1623            | 15
10637           | 16
13699           | 18
14421           | 18
16457           | 18
21717           | 18
31647           | 18
----------------------------------------

 Here is a comma-separated list of these numbers:

6, 8, 9, 10, 12, 14, 15, 16, 18, 27, 49, 63, 77, 119, 147, 153, 1011, 1099, 1209, 1623, 10637, 13699, 14421, 16457, 21717, 31647