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 A298918 #6 Jun 15 2020 14:00:27 %S A298918 0,4,1,3,9,19,31,199,330,1377,6627,23223,113179,849856,5207476, %T A298918 43357615 %N A298918 Number of n X n 0..1 arrays with every element equal to 1, 3, 5, 7 or 8 king-move adjacent elements, with upper left element zero. %C A298918 Diagonal of A298924. %e A298918 Some solutions for n=5 %e A298918 ..0..1..0..0..0. .0..0..0..0..0. .0..0..0..0..0. .0..0..1..1..1 %e A298918 ..0..1..0..0..0. .0..0..0..0..0. .0..0..0..0..0. .0..0..1..1..1 %e A298918 ..1..1..0..0..0. .0..0..0..0..0. .0..0..0..0..0. .0..0..1..1..1 %e A298918 ..0..1..0..0..0. .0..0..0..0..0. .1..1..1..1..1. .0..0..1..1..1 %e A298918 ..0..1..0..0..0. .0..0..0..0..0. .0..0..1..0..0. .0..0..1..1..1 %Y A298918 Cf. A298924. %K A298918 nonn %O A298918 1,2 %A A298918 _R. H. Hardin_, Jan 29 2018