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 A284340 #6 Apr 05 2020 22:58:03 %S A284340 64,1689,122495,14581112,1544903012,179138039472,20513380740103, %T A284340 2451428833201600,290448052609643641,35231200322704249292, %U A284340 4253729721779461810333,520640922794348063107735 %N A284340 Number of 7 X n 0..1 arrays with the number of 1's horizontally, diagonally or antidiagonally adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero. %C A284340 Row 7 of A284334. %H A284340 R. H. Hardin, <a href="/A284340/b284340.txt">Table of n, a(n) for n = 1..14</a> %e A284340 Some solutions for n=3 %e A284340 ..0..1..1. .0..1..0. .0..1..1. .0..0..0. .0..0..0. .0..0..1. .0..1..1 %e A284340 ..0..0..0. .1..1..0. .1..0..0. .0..0..0. .1..0..0. .0..0..1. .0..0..0 %e A284340 ..1..1..1. .1..0..0. .0..1..1. .0..1..1. .0..0..1. .1..1..1. .1..1..0 %e A284340 ..0..1..1. .1..0..1. .0..1..0. .0..1..0. .0..1..1. .0..0..1. .1..0..0 %e A284340 ..0..0..1. .0..0..0. .1..0..1. .1..1..1. .1..0..1. .0..1..0. .1..1..0 %e A284340 ..0..0..1. .1..1..1. .0..0..0. .0..0..0. .0..0..1. .1..1..1. .1..1..1 %e A284340 ..0..0..0. .1..1..1. .1..0..0. .1..1..1. .0..1..1. .0..1..0. .0..1..1 %Y A284340 Cf. A284334. %K A284340 nonn %O A284340 1,1 %A A284340 _R. H. Hardin_, Mar 25 2017