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 A303248 #6 Sep 16 2020 19:04:14 %S A303248 0,3,49,1401,106803,19457754,7600681910,7516309079483, %T A303248 16637614325062889 %N A303248 Number of n X n 0..1 arrays with every element equal to 1, 2, 3, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A303248 Diagonal of A303254. %e A303248 Some solutions for n=5 %e A303248 ..0..0..1..1..0. .0..0..0..0..1. .0..1..1..1..0. .0..0..0..0..1 %e A303248 ..0..0..1..0..1. .1..1..0..1..1. .1..0..0..0..1. .1..1..1..1..1 %e A303248 ..1..0..0..1..1. .1..0..0..1..1. .1..0..1..1..0. .1..0..0..0..0 %e A303248 ..1..1..0..1..0. .1..0..0..0..0. .0..1..0..1..1. .0..1..1..1..0 %e A303248 ..0..0..1..0..0. .1..1..1..1..1. .1..0..0..1..1. .0..0..0..0..1 %Y A303248 Cf. A303254. %K A303248 nonn %O A303248 1,2 %A A303248 _R. H. Hardin_, Apr 20 2018