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 A196473 #8 Jun 02 2025 04:24:47 %S A196473 1,5,7,35,151,5955,299659,8943355,528624118,48720477449 %N A196473 Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 4,0,3,2,1 for x=0,1,2,3,4. %C A196473 Every 0 is next to 0 4's, every 1 is next to 1 0's, every 2 is next to 2 3's, every 3 is next to 3 2's, every 4 is next to 4 1's %C A196473 Diagonal of A196477 %e A196473 Some solutions for n=4 %e A196473 ..1..0..0..1....0..0..0..0....0..0..1..1....0..0..0..0....0..0..0..1 %e A196473 ..1..1..1..1....0..0..0..0....1..1..1..0....1..1..1..1....1..1..1..1 %e A196473 ..0..1..1..0....0..0..0..0....1..1..1..1....1..1..1..1....1..1..1..0 %e A196473 ..0..1..1..0....1..1..1..1....0..0..0..1....0..0..0..0....0..0..1..1 %K A196473 nonn %O A196473 1,2 %A A196473 _R. H. Hardin_ Oct 03 2011