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 A284448 #6 Apr 06 2020 00:34:34 %S A284448 0,0,102,3384,4190874,3177012844,45913351929099,746140228341333064, %T A284448 140666601117969492988244 %N A284448 Number of n X n 0..1 arrays with the number of 1's king-move adjacent to some 0 one less than the number of 0's adjacent to some 1. %C A284448 Diagonal of A284455. %e A284448 Some solutions for n=4 %e A284448 ..1..1..0..0. .1..1..0..0. .0..1..0..0. .0..0..1..0. .0..0..0..0 %e A284448 ..0..0..0..1. .1..1..1..0. .0..1..1..1. .0..1..0..0. .0..1..1..0 %e A284448 ..1..1..0..0. .1..0..0..0. .0..0..1..0. .1..1..0..1. .1..1..0..0 %e A284448 ..1..1..0..1. .0..1..0..1. .0..0..1..1. .1..1..0..1. .1..1..1..1 %Y A284448 Cf. A284455. %K A284448 nonn %O A284448 1,3 %A A284448 _R. H. Hardin_, Mar 27 2017