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 A197887 #7 Jun 02 2025 05:12:56 %S A197887 1,43,196,2263,17890,129294,1134527,9389938,74334188,612587633, %T A197887 4957017898,40458420396,328259829544,2682720603080,21878875862100, %U A197887 178129467799644,1450139820586951,11818051611475707,96281373184386270 %N A197887 Number of nX6 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 0,2,1,1,1 for x=0,1,2,3,4. %C A197887 Every 0 is next to 0 0's, every 1 is next to 1 2'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 A197887 Column 6 of A197889 %H A197887 R. H. Hardin, <a href="/A197887/b197887.txt">Table of n, a(n) for n = 1..184</a> %e A197887 Some solutions containing all values 0 to 4 for n=4 %e A197887 ..1..2..2..1..0..1....0..1..2..2..1..0....1..2..0..1..1..0....1..2..2..1..0..1 %e A197887 ..3..1..1..4..1..2....2..1..1..1..3..1....3..1..1..2..2..1....3..1..1..4..1..2 %e A197887 ..1..3..3..1..1..0....1..4..1..1..0..2....1..4..1..2..0..1....1..3..3..1..1..2 %e A197887 ..2..1..1..2..2..1....0..1..2..2..1..1....2..1..3..1..1..2....2..1..1..2..0..1 %K A197887 nonn %O A197887 1,2 %A A197887 _R. H. Hardin_ Oct 19 2011