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 A275497 #6 Apr 21 2020 12:46:24 %S A275497 1,9,80,656,4180,68080,1643372,58423188,3045734096,235680645520, %T A275497 26923774835716,4558306996574952 %N A275497 Number of n X n 0..2 arrays with no element equal to any value at offset (-2,-1), (-2,0) or (-1,-1) and new values introduced in order 0..2. %C A275497 Diagonal of A275504. %e A275497 Some solutions for n=4 %e A275497 ..0..0..0..1. .0..1..2..2. .0..0..0..0. .0..1..2..2. .0..1..2..1 %e A275497 ..2..1..1..1. .0..2..2..0. .0..1..1..1. .1..1..2..0. .0..1..2..0 %e A275497 ..2..1..2..2. .2..2..0..1. .1..1..2..2. .1..2..0..0. .1..2..0..0 %e A275497 ..0..0..0..0. .2..1..0..1. .2..2..2..0. .2..0..0..1. .1..2..0..1 %Y A275497 Cf. A275504. %K A275497 nonn %O A275497 1,2 %A A275497 _R. H. Hardin_, Jul 30 2016