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 A300209 #6 Jun 15 2020 15:08:47 %S A300209 1,8,228,22194,7452385,8664017314,34824178698922,483558835111191345, %T A300209 23194796188589638077072 %N A300209 Number of n X n 0..1 arrays with every element equal to 0, 1, 2, 3, 4, 5, 7 or 8 king-move adjacent elements, with upper left element zero. %C A300209 Diagonal of A300215. %e A300209 Some solutions for n=5 %e A300209 ..0..0..0..0..0. .0..0..0..0..0. .0..0..0..0..0. .0..0..0..0..0 %e A300209 ..0..1..0..1..0. .0..1..0..1..1. .0..1..0..0..0. .0..0..0..0..1 %e A300209 ..1..0..1..0..1. .0..1..0..0..0. .0..1..1..1..1. .0..0..1..0..1 %e A300209 ..0..1..1..0..1. .0..1..0..1..0. .0..1..1..0..1. .0..0..0..1..1 %e A300209 ..0..0..0..0..0. .1..1..1..1..0. .1..0..0..1..1. .0..1..1..1..0 %Y A300209 Cf. A300215. %K A300209 nonn %O A300209 1,2 %A A300209 _R. H. Hardin_, Feb 28 2018