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 A297295 #7 Apr 19 2020 23:55:13 %S A297295 1,1,3,10,49,495,13504,629563,40753529,4162842319,790491998237, %T A297295 268041967942170,155466640607601204,159960976273554094907, %U A297295 300474954115694463716874,1003924486221768324971576564 %N A297295 Number of n X n 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 2 neighboring 1's. %C A297295 Diagonal of A297299. %H A297295 R. H. Hardin, <a href="/A297295/b297295.txt">Table of n, a(n) for n = 1..21</a> %e A297295 Some solutions for n=5 %e A297295 ..0..0..1..1..0. .0..0..0..0..0. .0..0..0..1..1. .0..1..1..0..0 %e A297295 ..0..1..1..0..0. .0..0..0..0..0. .0..0..1..1..0. .1..1..0..0..0 %e A297295 ..0..0..0..0..0. .0..1..1..0..0. .0..0..0..0..0. .0..1..1..0..0 %e A297295 ..0..0..1..1..0. .1..1..0..1..1. .0..0..0..0..0. .1..1..0..1..1 %e A297295 ..0..1..1..0..0. .0..0..1..1..0. .0..0..0..0..0. .0..0..1..1..0 %Y A297295 Cf. A297299. %K A297295 nonn %O A297295 1,3 %A A297295 _R. H. Hardin_, Dec 27 2017