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 A293080 #7 Apr 05 2020 23:36:13 %S A293080 0,0,53,8108,3786544,6736259130,48001754870966,1383438455350705382, %T A293080 161312497547006248372814,76023645347398961263283802334, %U A293080 144620752785016707502340606159808938 %N A293080 Number of n X n 0..1 arrays with the number of 1's horizontally or antidiagonally adjacent to some 0 two less than the number of 0's adjacent to some 1. %C A293080 Diagonal of A293087. %H A293080 R. H. Hardin, <a href="/A293080/b293080.txt">Table of n, a(n) for n = 1..12</a> %e A293080 Some solutions for n=4 %e A293080 ..1..1..1..0. .0..0..0..0. .0..1..1..0. .1..1..0..0. .0..1..1..0 %e A293080 ..0..1..1..0. .1..1..0..0. .0..0..1..1. .1..0..1..1. .0..0..0..1 %e A293080 ..0..0..1..0. .0..0..0..1. .0..0..0..1. .0..1..1..0. .1..0..0..1 %e A293080 ..0..0..0..1. .0..0..1..1. .0..0..1..0. .0..0..1..0. .0..1..1..0 %Y A293080 Cf. A293087. %K A293080 nonn %O A293080 1,3 %A A293080 _R. H. Hardin_, Sep 30 2017