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 A300366 #6 Jun 15 2020 15:11:12 %S A300366 0,1,0,3,32,366,12042,729062,70536528,13229207915,4795249162868 %N A300366 Number of n X n 0..1 arrays with every element equal to 2 or 3 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. %C A300366 Diagonal of A300372. %e A300366 Some solutions for n=5 %e A300366 ..0..0..1..0..0. .0..0..0..0..1. .0..0..0..0..1. .0..0..1..0..0 %e A300366 ..0..1..1..0..1. .0..1..0..1..1. .0..1..0..1..1. .0..1..1..0..1 %e A300366 ..0..0..0..1..1. .1..1..1..0..0. .1..1..1..0..0. .0..0..0..1..1 %e A300366 ..1..1..0..1..0. .0..0..1..0..1. .0..0..1..0..1. .0..1..0..1..0 %e A300366 ..1..1..0..0..0. .0..1..1..1..1. .0..0..1..1..1. .1..1..0..0..0 %Y A300366 Cf. A300372. %K A300366 nonn %O A300366 1,4 %A A300366 _R. H. Hardin_, Mar 04 2018