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 A385386 #5 Jun 29 2025 11:07:32 %S A385386 3,7,40,14,225,6432,26,1768,255451,43918404 %N A385386 Triangle read by rows: T(n,k) is the number of polysticks, i.e., connected nonempty subsets of edges, of the n X k flat torus, up to cyclic shifts and reflections of rows and columns; 1 <= k <= n. %C A385386 Two edges are connected if they share a vertex. %C A385386 Subsets that differ by interchanging rows and columns (when n = k) are considered distinct. For example, there are two distinct polysticks of size 1, one horizontal and one vertical. See A385389 for the analog of the main diagonal of this sequence in the case where such subsets are considered identical. %H A385386 Pontus von Brömssen, <a href="/A385386/a385386.png">Illustration for T(3,2)</a>. %e A385386 Triangle begins: %e A385386 n\k| 1 2 3 4 %e A385386 ---+------------------------ %e A385386 1 | 3 %e A385386 2 | 7 40 %e A385386 3 | 14 225 6432 %e A385386 4 | 26 1768 255451 43918404 %Y A385386 Cf. A385381 (polyominoes), A385387 (main diagonal), A385389. %K A385386 nonn,tabl,more %O A385386 1,1 %A A385386 _Pontus von Brömssen_, Jun 27 2025