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 A275125 #6 Apr 21 2020 12:43:23 %S A275125 1,4,45,568,12423,473185,31446544,3669759648,753079344538, %T A275125 270970785837211,171664742070518870,191385314222655170098 %N A275125 Number of n X n 0..2 arrays with no element equal to any value at offset (-2,-2), (-1,0) or (-1,1) and new values introduced in order 0..2. %C A275125 Diagonal of A275131. %e A275125 Some solutions for n=4 %e A275125 ..0..0..1..1. .0..1..0..2. .0..0..1..0. .0..0..0..1. .0..1..0..2 %e A275125 ..1..2..2..0. .2..2..1..1. .2..2..2..2. .2..2..2..2. .2..2..1..0 %e A275125 ..0..1..1..2. .0..0..2..2. .0..1..1..1. .1..0..1..1. .0..0..2..2 %e A275125 ..2..2..0..1. .1..1..1..0. .2..2..0..0. .2..2..0..0. .2..1..0..1 %Y A275125 Cf. A275131. %K A275125 nonn %O A275125 1,2 %A A275125 _R. H. Hardin_, Jul 17 2016