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 A302206 #6 Aug 20 2020 11:50:10 %S A302206 1,2,16,7,448,1395,55922,3509969,73189971,33707749345,2102356505182 %N A302206 Number of n X n 0..1 arrays with every element equal to 0, 2 or 3 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A302206 Diagonal of A302212. %e A302206 Some solutions for n=5 %e A302206 ..0..1..0..0..0. .0..1..0..0..1. .0..0..0..1..0. .0..0..1..1..0 %e A302206 ..1..1..1..0..1. .0..1..0..0..1. .1..0..1..1..1. .0..0..1..1..0 %e A302206 ..0..1..1..0..1. .1..1..1..0..0. .1..0..0..1..0. .1..0..1..1..0 %e A302206 ..0..1..0..0..0. .0..0..0..1..1. .1..0..0..1..0. .0..0..0..1..1 %e A302206 ..1..1..1..0..1. .0..0..1..1..0. .1..0..0..1..0. .1..0..0..1..1 %Y A302206 Cf. A302212. %K A302206 nonn %O A302206 1,2 %A A302206 _R. H. Hardin_, Apr 03 2018