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 A300083 #8 Jun 15 2020 15:05:59 %S A300083 1,4,1,25,415,1822,167131,14634300,1518807971,1088211703169 %N A300083 Number of n X n 0..1 arrays with every element equal to 0, 1, 3, 5, 6, 7 or 8 king-move adjacent elements, with upper left element zero. %C A300083 Diagonal of A300089. %e A300083 Some solutions for n=5 %e A300083 ..0..0..0..0..0. .0..1..1..0..1. .0..1..1..0..1. .0..1..0..1..0 %e A300083 ..0..0..0..0..0. .1..0..1..1..0. .0..1..1..0..1. .1..0..0..0..1 %e A300083 ..1..1..0..0..0. .1..1..1..1..1. .1..1..1..0..0. .1..1..1..1..1 %e A300083 ..1..1..0..0..0. .1..0..1..1..0. .0..1..1..0..1. .0..1..1..1..0 %e A300083 ..1..1..0..0..0. .0..1..1..0..1. .1..0..1..1..0. .0..1..1..1..0 %Y A300083 Cf. A300089. %K A300083 nonn %O A300083 1,2 %A A300083 _R. H. Hardin_, Feb 24 2018