This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A384378 #8 Jun 01 2025 16:38:26 %S A384378 2,4,7,12,10,6,2,1,2,4,9,17,28,25,16,7,2,1,4,7,20,47,123,274,531,779, %T A384378 758,504,241,87,22,4,1,4,7,20,51,144,382,990,2332,4873,8546,11776, %U A384378 11733,8529,4673,1957,639,156,31,4,1 %N A384378 Irregular triangle read by rows: T(n,k) is the number of connected subsets of k edges (or polysticks) of the n-th Johnson solid, up to symmetries of that solid; 1 <= n <= 92, 1 <= k <= A242732(n). %H A384378 Pontus von Brömssen, <a href="/A384378/b384378.txt">Table of n, a(n) for n = 1..78</a> (first 5 rows) %H A384378 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/JohnsonSolid.html">Johnson Solid</a>. %H A384378 Wikipedia, <a href="https://en.wikipedia.org/wiki/List_of_Johnson_solids">List of Johnson solids</a>. %e A384378 Triangle begins: %e A384378 n\k| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 %e A384378 ---+---------------------------------------------------------------------------------- %e A384378 1 | 2 4 7 12 10 6 2 1 %e A384378 2 | 2 4 9 17 28 25 16 7 2 1 %e A384378 3 | 4 7 20 47 123 274 531 779 758 504 241 87 22 4 1 %e A384378 4 | 4 7 20 51 144 382 990 2332 4873 8546 11776 11733 8529 4673 1957 639 156 31 4 1 %Y A384378 Cf. A242732 (row lengths), A384376, A384379 (row sums), A384380. %K A384378 nonn,tabf,fini %O A384378 1,1 %A A384378 _Pontus von Brömssen_ and _Peter Kagey_, May 28 2025