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 A196309 #8 Jun 02 2025 04:20:53 %S A196309 1,5,7,335,3349,184217,11575179,2915102103,766706823953, %T A196309 662820784405591 %N A196309 Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 2,0,4,1,3 for x=0,1,2,3,4. %C A196309 Every 0 is next to 0 2's, every 1 is next to 1 0's, every 2 is next to 2 4's, every 3 is next to 3 1's, every 4 is next to 4 3's %C A196309 Diagonal of A196314 %e A196309 Some solutions for n=4 %e A196309 ..0..0..1..1....1..1..0..0....0..1..1..0....0..1..1..0....1..1..0..1 %e A196309 ..1..3..1..0....0..3..1..1....1..3..3..1....0..1..1..0....0..1..3..1 %e A196309 ..1..1..1..0....0..1..1..3....3..1..1..1....1..1..1..1....0..3..1..0 %e A196309 ..0..0..1..1....1..1..0..1....1..0..0..0....1..0..0..1....0..1..3..1 %K A196309 nonn %O A196309 1,2 %A A196309 _R. H. Hardin_ Oct 01 2011