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 A284161 #6 Apr 05 2020 22:33:33 %S A284161 6,42,461,5888,80072,1142173,16699997,247899694,3717494360, %T A284161 56178550056,854108948176,13048507894281,200142020916533, %U A284161 3080098116131143,47536024103910119,735432363055523510,11402172535387288712 %N A284161 Number of n X 4 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 A284161 Column 4 of A284165. %H A284161 R. H. Hardin, <a href="/A284161/b284161.txt">Table of n, a(n) for n = 1..173</a> %e A284161 Some solutions for n=4 %e A284161 ..0..1..0..1. .0..0..0..0. .0..0..1..0. .0..1..0..0. .0..1..1..1 %e A284161 ..0..0..0..1. .1..1..1..1. .1..1..0..1. .0..1..0..0. .0..0..1..0 %e A284161 ..1..1..1..0. .1..0..1..0. .1..0..0..1. .1..0..1..1. .1..0..1..0 %e A284161 ..1..1..1..0. .1..0..1..0. .0..1..0..1. .1..1..0..1. .0..1..1..1 %Y A284161 Cf. A284165. %K A284161 nonn %O A284161 1,1 %A A284161 _R. H. Hardin_, Mar 21 2017