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 A299608 #6 Jun 15 2020 14:48:50 %S A299608 0,3,15,40,179,1223,13490,231838,6506278,335604816 %N A299608 Number of n X n 0..1 arrays with every element equal to 1, 2, 4, 6, 7 or 8 king-move adjacent elements, with upper left element zero. %C A299608 Diagonal of A299612. %e A299608 Some solutions for n=6 %e A299608 ..0..1..1..0..0..0. .0..0..1..0..1..1. .0..0..1..0..1..0. .0..0..1..1..0..1 %e A299608 ..0..0..0..0..0..1. .1..0..1..0..0..1. .1..0..1..0..1..0. .1..1..1..1..1..0 %e A299608 ..0..0..0..0..0..1. .1..1..1..1..1..1. .1..0..0..0..0..1. .0..0..1..1..1..1 %e A299608 ..1..0..0..0..0..0. .1..1..1..1..1..1. .0..1..0..0..0..0. .1..0..1..1..1..1 %e A299608 ..1..0..0..1..0..0. .0..1..1..1..1..0. .0..1..0..0..0..0. .0..1..0..0..1..0 %e A299608 ..1..0..1..0..1..0. .1..0..1..1..0..1. .0..1..0..1..1..0. .1..0..1..0..1..0 %Y A299608 Cf. A299612. %K A299608 nonn %O A299608 1,2 %A A299608 _R. H. Hardin_, Feb 14 2018