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 A197195 #8 Jun 02 2025 04:45:58 %S A197195 1,5,25,314,7363,350711,33176391,6258308430,2359068239358, %T A197195 1774609159901861 %N A197195 Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 4,1,3,2,0 for x=0,1,2,3,4. %C A197195 Every 0 is next to 0 4's, every 1 is next to 1 1's, every 2 is next to 2 3's, every 3 is next to 3 2's, every 4 is next to 4 0's %C A197195 Diagonal of A197199 %e A197195 Some solutions for n=4 %e A197195 ..0..0..0..1....0..0..0..1....1..1..0..0....0..1..1..0....0..0..1..0 %e A197195 ..1..1..0..1....0..0..0..1....0..0..0..0....1..0..0..0....1..0..1..0 %e A197195 ..0..0..1..0....1..1..0..0....1..1..0..0....1..0..1..0....1..0..0..1 %e A197195 ..0..0..1..0....0..0..1..1....0..0..0..0....0..0..1..0....0..0..0..1 %K A197195 nonn %O A197195 1,2 %A A197195 _R. H. Hardin_ Oct 11 2011