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 A275177 #6 Apr 21 2020 12:43:57 %S A275177 1,4,25,141,1465,23313,561044,20397794,1120217646,93298660085, %T A275177 11806084302586,2272026396983803,664988521276834246 %N A275177 Number of n X n 0..2 arrays with no element equal to any value at offset (-2,-1), (-1,0) or (-1,1) and new values introduced in order 0..2. %C A275177 Diagonal of A275183. %e A275177 Some solutions for n=4 %e A275177 ..0..0..1..2. .0..0..0..1. .0..0..0..1. .0..0..0..1. .0..0..0..1 %e A275177 ..2..2..0..1. .2..2..2..0. .1..2..2..0. .1..2..2..0. .1..2..2..0 %e A275177 ..0..1..2..2. .0..1..1..2. .0..1..1..2. .0..1..1..1. .0..1..1..2 %e A275177 ..2..0..0..1. .2..0..0..1. .2..0..0..1. .2..0..0..0. .2..2..0..0 %Y A275177 Cf. A275183. %K A275177 nonn %O A275177 1,2 %A A275177 _R. H. Hardin_, Jul 19 2016