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 A196849 #8 Jun 02 2025 04:34:57 %S A196849 1,11,206,16876,4326720,3805929995,11300853019444,113522093851497024 %N A196849 Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 3,1,0,2,4 for x=0,1,2,3,4. %C A196849 Every 0 is next to 0 3's, every 1 is next to 1 1's, every 2 is next to 2 0's, every 3 is next to 3 2's, every 4 is next to 4 4's %C A196849 Diagonal of A196856 %e A196849 Some solutions for n=4 %e A196849 ..0..0..0..0....0..0..1..1....0..0..0..2....0..1..1..0....0..0..0..0 %e A196849 ..2..0..0..2....0..0..0..0....2..0..0..0....0..0..0..0....0..0..1..1 %e A196849 ..1..1..0..1....2..2..2..1....2..0..2..2....2..1..2..1....1..1..2..0 %e A196849 ..0..0..0..1....0..0..0..1....0..1..1..0....0..1..0..1....0..0..0..0 %K A196849 nonn %O A196849 1,2 %A A196849 _R. H. Hardin_ Oct 06 2011