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 A268977 #4 Feb 16 2016 13:58:29 %S A268977 2187,184320,5598720,167226768,4823705520,137497776840,3870355944960, %T A268977 107884943899488,2981278225929744,81772049776604472, %U A268977 2228316762081730176,60378377050028640600,1627890867639031100112,43698886755490031302440 %N A268977 Number of 7Xn 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once. %C A268977 Row 7 of A268971. %H A268977 R. H. Hardin, <a href="/A268977/b268977.txt">Table of n, a(n) for n = 1..210</a> %H A268977 R. H. Hardin, <a href="/A268977/a268977.txt">Empirical recurrence of order 54</a> %F A268977 Empirical recurrence of order 54 (see link above) %e A268977 Some solutions for n=2 %e A268977 ..0..0. .2..0. .0..0. .0..1. .1..0. .1..0. .0..0. .1..1. .1..0. .0..1 %e A268977 ..1..0. .1..2. .1..2. .1..0. .1..2. .0..1. .0..1. .2..2. .0..1. .0..2 %e A268977 ..1..1. .1..0. .2..2. .0..1. .1..2. .2..2. .2..2. .1..2. .0..1. .1..2 %e A268977 ..0..0. .0..0. .2..1. .2..1. .0..0. .2..1. .1..0. .1..0. .2..1. .2..2 %e A268977 ..0..1. .0..0. .2..2. .2..1. .1..2. .0..2. .1..2. .1..0. .0..0. .1..0 %e A268977 ..2..1. .0..1. .0..1. .2..2. .2..2. .1..2. .2..1. .0..1. .0..1. .0..1 %e A268977 ..2..2. .2..1. .2..2. .1..0. .2..2. .1..0. .0..1. .2..2. .0..0. .2..2 %Y A268977 Cf. A268971. %K A268977 nonn %O A268977 1,1 %A A268977 _R. H. Hardin_, Feb 16 2016