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 A197886 #7 Jun 02 2025 05:12:51 %S A197886 1,18,77,835,2730,17890,92843,567991,3000116,17111462,94740977, %T A197886 537643352,2995145891,16728999681,93489922434,524952952537, %U A197886 2940191924830,16425787144594,91861015115420,514650900540840,2882700958009902 %N A197886 Number of nX5 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 A197886 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 A197886 Column 5 of A197889 %H A197886 R. H. Hardin, <a href="/A197886/b197886.txt">Table of n, a(n) for n = 1..210</a> %e A197886 Some solutions containing all values 0 to 4 for n=4 %e A197886 ..2..1..0..1..2....1..2..2..1..0....1..2..2..1..1....2..1..0..1..2 %e A197886 ..1..0..2..1..1....0..1..1..1..2....0..1..1..0..2....1..0..2..1..1 %e A197886 ..1..3..1..4..1....2..1..4..1..1....2..1..4..1..1....3..1..1..4..1 %e A197886 ..2..1..0..1..2....1..3..1..2..0....1..3..1..2..0....1..2..0..1..2 %K A197886 nonn %O A197886 1,2 %A A197886 _R. H. Hardin_ Oct 19 2011