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 A293089 #6 Apr 05 2020 23:41:40 %S A293089 0,1,53,486,4091,32070,246852,1897509,14578434,112390406,867693603, %T A293089 6716080364,52061270779,404329966577,3144612848086,24493415901992, %U A293089 191015933608631,1491484435347360,11658153191250672,91217811828544156 %N A293089 Number of 3 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 A293089 Row 3 of A293087. %H A293089 R. H. Hardin, <a href="/A293089/b293089.txt">Table of n, a(n) for n = 1..210</a> %e A293089 Some solutions for n=4 %e A293089 ..0..0..0..0. .0..0..1..0. .0..1..0..0. .0..0..0..0. .0..1..0..0 %e A293089 ..1..0..1..0. .0..1..0..1. .0..1..0..0. .0..1..1..0. .0..1..1..0 %e A293089 ..0..1..1..0. .1..0..0..0. .0..1..1..1. .1..0..1..0. .1..0..1..0 %Y A293089 Cf. A293087. %K A293089 nonn %O A293089 1,3 %A A293089 _R. H. Hardin_, Sep 30 2017