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 A197243 #8 Jun 02 2025 04:48:25 %S A197243 1,4,3,275,5062,405065,48703999,11304892092,9455531359836, %T A197243 13086658688226332 %N A197243 Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 0,0,1,1,1 for x=0,1,2,3,4. %C A197243 Every 0 is next to 0 0's, every 1 is next to 1 0's, every 2 is next to 2 1's, every 3 is next to 3 1's, every 4 is next to 4 1's %C A197243 Diagonal of A197250 %e A197243 All solutions containing all values 0 to 4 for n=4 %e A197243 ..0..1..3..1....1..0..1..2....1..3..1..0....2..1..0..1 %e A197243 ..1..4..1..0....3..1..4..1....0..1..4..1....1..4..1..3 %e A197243 ..3..1..4..1....1..4..1..0....1..4..1..3....0..1..4..1 %e A197243 ..1..0..1..2....0..1..3..1....2..1..0..1....1..3..1..0 %K A197243 nonn %O A197243 1,2 %A A197243 _R. H. Hardin_ Oct 12 2011