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 A282640 #6 Apr 26 2020 20:38:55 %S A282640 2,11,99,2638,133118,15985259,4257307148,2506410920603, %T A282640 3330699748741870,9838180083513076754,65038588812750477539631, %U A282640 960673982564908731679446423,31695946605234699442469207411170 %N A282640 Number of n X n 0..1 arrays with no 1 equal to more than one of its king-move neighbors. %C A282640 Diagonal of A282647. %e A282640 Some solutions for n=4 %e A282640 ..1..0..1..0. .0..0..0..1. .1..0..1..0. .0..0..0..0. .0..0..0..1 %e A282640 ..0..0..0..0. .0..0..1..0. .0..0..1..0. .0..1..0..1. .0..0..1..0 %e A282640 ..1..1..0..1. .1..0..0..0. .1..0..0..0. .0..0..0..0. .1..0..0..0 %e A282640 ..0..0..0..1. .0..0..0..1. .1..0..0..1. .0..0..1..0. .0..0..1..0 %Y A282640 Cf. A282647. %K A282640 nonn %O A282640 1,1 %A A282640 _R. H. Hardin_, Feb 20 2017