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 A188740 #8 Jul 22 2025 11:19:48 %S A188740 2,16,292,17286,3283906,1536573216,2307086087740,10143499802360135, %T A188740 123466985032906186049,4528058434298770108386326, %U A188740 481947777827695507476795332215,147455854241909275954639647341005231 %N A188740 Number of n X n binary arrays without the pattern 1 1 1 diagonally, vertically or antidiagonally. %C A188740 Diagonal of A188747 %e A188740 Some solutions for 3X3 %e A188740 ..0..0..0....0..1..1....0..0..0....0..0..0....1..0..0....0..1..0....1..0..0 %e A188740 ..1..0..0....1..0..0....0..1..1....1..1..1....0..1..1....0..0..0....0..0..0 %e A188740 ..0..0..0....1..0..0....1..1..1....0..0..0....0..0..0....0..1..0....1..1..1 %K A188740 nonn %O A188740 1,1 %A A188740 _R. H. Hardin_ Apr 09 2011