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 A356049 #46 Jul 28 2022 09:22:10 %S A356049 1,5,5,15,57,15,41,489,489,41,113,4125,12675,4125,113,313,35117, %T A356049 321689,321689,35117,313,867,299681,8180343,24318165,8180343,299681, %U A356049 867,2401,2557605,208144601,1840058693,1840058693,208144601,2557605,2401 %N A356049 Symmetric array read by antidiagonals: T(n,k) is the number of legal positions in Go on an n X k board. %C A356049 A Go position is a grid containing white and black stones with the condition that every orthogonally connected group of stones of a single color has liberties, i.e., is orthogonally adjacent to an empty cell. %H A356049 Douglas Boffey, <a href="/A356049/b356049.txt">Table of n, a(n) for n = 1..528</a> %H A356049 J. Tromp, <a href="https://tromp.github.io/go/legal.html">Number of Legal Go Positions</a> %e A356049 Array begins: %e A356049 1, 5, 15, 41, ... %e A356049 5, 57, 489, ... %e A356049 15, 489, ... %e A356049 41, ... %e A356049 ... %e A356049 T(3,1) = 15 from %e A356049 ... ..w ..b .w. .ww .b. .bb w.. w.w w.b ww. b.. b.w b.b bb. %Y A356049 Columns (or rows) give: A102620, A266278. %Y A356049 Main diagonal gives A094777. %Y A356049 This as triangle gives A356134. %K A356049 nonn,tabl %O A356049 1,2 %A A356049 _Douglas Boffey_, Jul 24 2022