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 A196803 #8 Jan 01 2024 19:50:50 %S A196803 1,1,16,193,19449,2535368,1436535356,2099296647197,9043086011797968, %T A196803 109561680407727718539 %N A196803 Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 4,2,3,0,1 for x=0,1,2,3,4. %C A196803 Every 0 is next to 0 4's, every 1 is next to 1 2's, every 2 is next to 2 3's, every 3 is next to 3 0's, every 4 is next to 4 1's. %C A196803 Diagonal of A196809. %e A196803 Some solutions for n=4 %e A196803 ..0..0..0..0....0..0..1..0....0..3..0..0....0..1..0..0....0..3..0..0 %e A196803 ..0..3..0..0....0..3..2..0....0..0..0..0....0..2..3..0....0..0..3..0 %e A196803 ..1..2..3..0....3..0..3..0....3..0..0..3....0..3..0..3....0..0..3..0 %e A196803 ..0..0..0..0....0..3..0..0....0..0..0..0....0..0..0..0....0..3..0..0 %Y A196803 Cf. A196809. %K A196803 nonn %O A196803 1,3 %A A196803 _R. H. Hardin_, Oct 06 2011