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 A285023 #6 Apr 06 2020 00:35:56 %S A285023 0,2,97,6460,3708321,5075612300,40651048407879,1063834786036208904, %T A285023 129443742138071637706453 %N A285023 Number of n X n 0..1 arrays with the number of 1's horizontally, antidiagonally or vertically adjacent to some 0 one less than the number of 0's adjacent to some 1. %C A285023 Diagonal of A285030. %e A285023 Some solutions for n=4 %e A285023 ..0..1..0..1. .1..1..0..0. .0..1..0..1. .0..0..0..1. .0..1..1..1 %e A285023 ..1..1..1..0. .1..1..0..1. .1..1..0..0. .0..1..0..0. .1..1..0..0 %e A285023 ..0..0..0..1. .0..0..0..1. .1..1..0..0. .1..1..1..0. .0..0..1..0 %e A285023 ..0..0..1..0. .0..0..1..1. .1..0..1..0. .0..1..0..1. .1..0..0..0 %Y A285023 Cf. A285030. %K A285023 nonn %O A285023 1,2 %A A285023 _R. H. Hardin_, Apr 08 2017