# oeis Published articles for oeis. This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles. ## More whimsical OEIS sequences DevFeed: [More whimsical OEIS sequences]() Original publisher: [Read original article]() Published: 2026-05-22T22:28:34Z Content type: opinion Language: en Sources: [Jeremy Kun]() Topics: [Sequences]() Tags: [depths-of-oeis](), [doom](), [oeis](), [sequences](), [shortform](), [xkcd]() ### AI overview An informal survey of whimsical OEIS sequences, including sequences inspired by XKCD, non-reduced fractions, hexadecimal patterns, James Bond primes, random tables, and references to the number 666. ### Source excerpt Here are some more whimsical OEIS sequences I came across. XKCD 2016 joked that "OEIS keeps rejecting my submissions," including one that gives "Integers in increasing order of width when printed in Helvetica." Well, two days after that comic was published (2018-07-09), Hugo Pfoertner published A316600, with a very precise definition. Then he did Arial. Randall Munroe missed a huge opportunity to commit to his bit and actually try to submit some of his sequences before publishing the comic. ## Unusual uses of OEIS sequences on GitHub DevFeed: [Unusual uses of OEIS sequences on GitHub]() Original publisher: [Read original article]() Published: 2026-04-13T14:00:00Z Content type: opinion Language: en Sources: [Jeremy Kun]() Topics: [Sequences](), [Open Source](), [GitHub](), [Algorithms]() Tags: [algorithms](), [code](), [coding](), [depths-of-oeis](), [github](), [oeis](), [open-source](), [sequences](), [shortform]() ### AI overview The article surveys unusual uses of OEIS sequences in open-source software on GitHub. It describes their use in the Mercury and Ziffers live-coding music frameworks, the Plato e-reader's pen-size options, and the GC Wizard geocaching app. ### Source excerpt I went hunting for references to the OEIS in open source code, and found some weird ones. There are not one, but two live-coding music frameworks that use OEIS sequences as a source for "anything that can be sequenced" in music. I'm guessing that's used for choosing pseudorandom melodies, interesting rhythyms, or how to overlap tracks in different ways. The first project is called mercury, which is advertised as having "an extensive library of algorithms to generate or transform numbersequences that can modulate parameters. ## The OEIS meta sequence and subway stations DevFeed: [The OEIS meta sequence and subway stations]() Original publisher: [Read original article]() Published: 2026-04-09T13:55:17Z Content type: opinion Language: en Sources: [Jeremy Kun]() Topics: [Sequences](), [math](), [Database]() Tags: [database](), [depths-of-oeis](), [new-york-city](), [numberphile](), [oeis](), [quirk](), [sequence](), [sequences](), [shortform](), [train]() ### AI overview This commentary examines OEIS sequence A051070, whose nth term is the nth entry of sequence A_n, or -1 when that sequence lacks enough terms. It highlights unusually large or unknown values, subway-stop sequences included in the OEIS, and self-referential questions involving A051070 and A102288. ### Source excerpt A051070 is a sequence about OEIS sequences. a(n) is the n-th term in sequence A_n (or -1 if A_n doesn't have enough terms). So the first term in A051070 is 1 because A000001 is the number of groups of order n, and that sequence has 1 as its entry in index 1. A000002 is the Kolakoski sequence (what? For another time) and has value 2 in entry 2. The sequence continues: 1, 2, 1, 0, 2, 3, 0, 7, 8, 4, 63, 1, 316, ... ## Deterministic Primality Testing for Limited Bit Width DevFeed: [Deterministic Primality Testing for Limited Bit Width]() Original publisher: [Read original article]() Published: 2026-04-07T13:00:00Z Content type: tutorial Language: en Sources: [Jeremy Kun]() Topics: [Algorithms](), [C++](), [Mathematics](), [Cryptography](), [homomorphic encryption]() Tags: [algorithm](), [c-plus-plus](), [code](), [cryptography](), [homomorphic-encryption](), [mathematics](), [miller-rabin](), [oeis](), [primes](), [programming](), [randomized-algorithm]() ### AI overview This article explains how to perform deterministic Miller-Rabin primality testing for 32-bit integers. It presents C++ code using the bases 2, 3, 5, and 7, which the article states is deterministic for all 32-bit inputs, and discusses strong pseudoprimes and related research. ### Source excerpt Problem: Determine if a 32-bit number is prime (deterministically) Solution: (in C++) // Bases to test. Using the first 4 prime bases makes the test deterministic // for all 32-bit integers. See https://oeis.org/A014233. int64_t bases[] = {2, 3, 5, 7}; inline int countTrailingZeros(uint64_t n) { if (n == 0) return 64; return __builtin_ctzll(n); } int64_t modularExponentiation(int64_t base, int64_t exponent, int64_t modulus) { int64_t res = 1; int64_t b = base % modulus; int64_t e = exponent; while (e > 0) { if (e & 1) { // Doesn't overflow because we assume 32-bit integer inputs res = (res * b) % modulus; } b = (b * b) % modulus; e >>= 1; } return res; } bool isPrime(int64_t n) { if (n < 2) return false; if (n < 4) return true; if (! ## Carnival of Mathematics #209 DevFeed: [Carnival of Mathematics #209]() Original publisher: [Read original article]() Published: 2022-10-02T08:00:00Z Content type: article Language: en Sources: [Jeremy Kun]() Topics: [math](), [Graphs](), [Networks](), [Cryptography](), [Post-Quantum](), [Icons](), [function](), [Mazes]() Tags: [carnival](), [cryptography](), [function](), [graphs](), [knot-theory](), [math](), [mathematics](), [matrix](), [networks](), [oeis](), [post-quantum](), [sieve](), [umap]() ### AI overview The 209th Carnival of Mathematics highlights mathematical properties of the number 209 and curates videos, talks, workshops, and social-media discussions covering mathematical visualization, pi, geometric puzzles, graph limits, random graphs, network models, post-quantum cryptography, and related topics. ### Source excerpt Welcome to the 209th Carnival of Mathematics! 209 has a few distinctions, including being the smallest number with 6 representations as a sum of 3 positive squares: $$\begin{aligned}209 &= 1^2 + 8^2 + 12^2 \\\ &= 2^2 + 3^2 + 14^2 \\\ &= 2^2 + 6^2 + 13^2 \\\ &= 3^2 + 10^2 + 10^2 \\\ &= 4^2 + 7^2 + 12^2 \\\ &= 8^2 + 8^2 + 9^2 \end{aligned}$$ As well as being the 43rd Ulam number, the number of partitions of 16 into relatively prime parts and the number of partitions of 63 into squares. ## Carnival of Mathematics #197 DevFeed: [Carnival of Mathematics #197]() Original publisher: [Read original article]() Published: 2021-09-01T08:00:00Z Content type: article Language: en Sources: [Jeremy Kun]() Topics: [Mathematics](), [Graphics](), [Simulation](), [Data Science]() Tags: [carnival](), [dataset](), [fibonacci](), [folding](), [functional-analysis](), [geometric-series](), [graphics](), [inner-product](), [knot-theory](), [mathematics](), [oeis](), [sequence](), [sieve](), [simulation](), [umap](), [visualization]() ### AI overview The 197th Carnival of Mathematics introduces the number 197 and highlights mathematical and technical topics including curve untangling, folding equilateral triangles without measurement, and criticism of UMAP and t-SNE dimensionality reduction. ### Source excerpt Welcome to the 197th Carnival of Mathematics! 197 is an unseemly number, as you can tell by the Wikipedia page which currently says that it has "indiscriminate, excessive, or irrelevant examples." How deviant. It's also a Repfigit, which means if you start a fibonacci-type sequence with the digits 1, 9, 7, and then continue with $ a_n = a_{i-3} + a_{i-2} + a_{i-1}$, then 197 shows up in the sequence. Indeed: 1, 9, 7, 17, 33, 57, 107, 197, ... ## Searching for RH Counterexamples -- Adding a Database DevFeed: [Searching for RH Counterexamples -- Adding a Database]() Original publisher: [Read original article]() Published: 2020-09-11T18:53:48Z Content type: tutorial Language: en Sources: [Jeremy Kun]() Topics: [Database](), [Software Engineering](), [Code](), [interface](), [Testing](), [Git]() Tags: [code](), [database](), [databases](), [dependency](), [git](), [interface](), [mathematics](), [number-theory](), [oeis](), [programming](), [riemann-hypothesis](), [software](), [software-design](), [sql](), [testing]() ### AI overview This tutorial extends a Python application that computes divisor sums related to attempts to disprove the Riemann Hypothesis by adding a database dependency. It advocates defining and testing a minimal interface before choosing a database, so the dependency can change as the application evolves. ### Source excerpt In the last article we set up pytest for a simple application that computes divisor sums $ \sigma(n)$ and tries to disprove the Riemann Hypothesis. In this post we'll show how to extend the application as we add a database dependency. The database stores the computed sums so we can analyze them after our application finishes. As in the previous post, I'll link to specific git commits in the final code repository to show how the project evolves.