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 A286211 #6 Apr 05 2020 23:25:35 %S A286211 0,17,52,684,2128,34896,123541,1891998,7565509,106100847,470286934, %T A286211 6070072444,29342743563,352400491431,1833102380708,20699165970978, %U A286211 114576111229319,1227555854005393,7163217232141967,73387852919316000 %N A286211 Number of n X 3 0..1 arrays with the number of 1's king-move adjacent to some 0 two less than the number of 0's adjacent to some 1. %C A286211 Column 3 of A286216. %H A286211 R. H. Hardin, <a href="/A286211/b286211.txt">Table of n, a(n) for n = 1..210</a> %e A286211 Some solutions for n=4 %e A286211 ..1..0..0. .1..0..1. .0..1..1. .1..0..0. .1..1..0. .0..1..0. .0..0..1 %e A286211 ..0..1..0. .0..0..1. .1..0..0. .1..0..0. .1..0..0. .0..1..0. .0..0..0 %e A286211 ..0..1..1. .0..0..0. .1..0..0. .0..0..0. .0..0..0. .1..1..0. .0..0..1 %e A286211 ..0..0..1. .0..1..1. .0..1..0. .1..0..1. .1..0..0. .1..0..0. .1..1..0 %Y A286211 Cf. A286216. %K A286211 nonn %O A286211 1,2 %A A286211 _R. H. Hardin_, May 04 2017