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 A282878 #6 Apr 26 2020 20:40:46 %S A282878 0,2,74,3762,480995,128768496,79687436788,115172557654616, %T A282878 393143666098549156,3196549492640753656296,62216948503916625663186184 %N A282878 Number of n X n 0..1 arrays with no 1 equal to more than one of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly one element. %C A282878 Diagonal of A282885. %e A282878 Some solutions for n=4 %e A282878 ..1..0..0..1. .0..1..0..0. .1..0..1..0. .1..0..1..0. .1..0..0..1 %e A282878 ..1..0..1..0. .1..0..1..0. .0..1..0..0. .0..0..1..0. .0..0..0..1 %e A282878 ..0..1..0..0. .1..0..0..1. .0..0..0..1. .0..1..0..1. .1..0..0..0 %e A282878 ..0..0..0..0. .0..1..0..0. .0..1..1..0. .0..0..0..0. .0..1..1..1 %Y A282878 Cf. A282885. %K A282878 nonn %O A282878 1,2 %A A282878 _R. H. Hardin_, Feb 24 2017