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 A293099 #6 Apr 05 2020 23:48:25 %S A293099 3,2220,205195,24773296,2728695681,328979478088,38469698642410, %T A293099 4665971856266714,560706154294046909,68470475134869958112, %U A293099 8347937003432022928553,1025774531240519319091628 %N A293099 Number of n X 7 0..1 arrays with the number of 1's horizontally, diagonally or antidiagonally adjacent to some 0 two less than the number of 0's adjacent to some 1. %C A293099 Column 7 of A293100. %H A293099 R. H. Hardin, <a href="/A293099/b293099.txt">Table of n, a(n) for n = 1..25</a> %e A293099 Some solutions for n=2 %e A293099 ..0..0..1..0..0..0..0. .0..0..0..1..0..0..0. .0..1..0..0..0..0..1 %e A293099 ..0..0..1..0..1..1..1. .1..1..0..0..1..1..1. .0..1..0..0..1..1..1 %Y A293099 Cf. A293100. %K A293099 nonn %O A293099 1,1 %A A293099 _R. H. Hardin_, Sep 30 2017