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 A284108 #6 Apr 05 2020 22:29:07 %S A284108 3,13,25,435,1230,20275,67957,1057769,4091201,57977326,251405237, %T A284108 3267210309,15553103766,187647577263,965234391129,10933376520347, %U A284108 60012823834203,644348267987097,3735767137025182,38329302231936856 %N A284108 Number of n X 3 0..1 arrays with the number of 1's king-move adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero. %C A284108 Column 3 of A284113. %H A284108 R. H. Hardin, <a href="/A284108/b284108.txt">Table of n, a(n) for n = 1..210</a> %e A284108 Some solutions for n=4 %e A284108 ..0..1..0. .0..0..1. .0..1..1. .0..1..1. .0..1..1. .0..1..1. .0..0..0 %e A284108 ..0..1..0. .1..1..0. .1..0..1. .0..0..1. .0..0..0. .1..0..0. .1..1..1 %e A284108 ..1..0..1. .1..0..0. .0..0..0. .1..0..0. .1..1..0. .1..1..0. .1..1..1 %e A284108 ..1..0..1. .1..1..0. .1..0..1. .1..1..0. .0..1..1. .0..1..0. .0..0..0 %Y A284108 Cf. A284113. %K A284108 nonn %O A284108 1,1 %A A284108 _R. H. Hardin_, Mar 20 2017