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 A284159 #6 Apr 05 2020 21:32:48 %S A284159 2,4,13,42,134,467,1689,6210,23178,87336,331172,1262635,4836199, %T A284159 18592719,71697865,277195002,1074041216,4169581090,16214541562, %U A284159 63150645344,246288102302,961707595682,3759467766802,14711266580343,57620439699189 %N A284159 Number of n X 2 0..1 arrays with the number of 1's horizontally or vertically adjacent to some 0 equal to the number of 0's adjacent to some 1, with top left element zero. %C A284159 Column 2 of A284165. %H A284159 R. H. Hardin, <a href="/A284159/b284159.txt">Table of n, a(n) for n = 1..210</a> %e A284159 Some solutions for n=4 %e A284159 ..0..0. .0..0. .0..1. .0..1. .0..0. .0..1. .0..1. .0..1. .0..1. .0..1 %e A284159 ..0..0. .0..1. .1..0. .1..0. .0..0. .1..0. .0..1. .0..1. .0..0. .1..1 %e A284159 ..0..1. .1..1. .0..1. .1..0. .1..1. .1..1. .0..0. .0..1. .1..1. .0..0 %e A284159 ..1..1. .1..1. .1..0. .0..1. .1..1. .0..0. .1..1. .1..0. .0..1. .0..1 %Y A284159 Cf. A284165. %K A284159 nonn %O A284159 1,1 %A A284159 _R. H. Hardin_, Mar 21 2017