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 A197278 #11 Aug 25 2025 15:04:40 %S A197278 16,134,888,11850,114205,1276986,13500114,135563958,1464662469, %T A197278 15975572837,167590942240,1768832921236,19029812782209, %U A197278 203511535493020,2157669619156227,22971322152723986,245668877166018309,2619846491701562613,27883612518177103171,297316240949616974969 %N A197278 Number of n X 6 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,0,1,1,1 for x=0,1,2,3,4. %C A197278 Every 0 is next to 0 2'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 %H A197278 R. H. Hardin, <a href="/A197278/b197278.txt">Table of n, a(n) for n = 1..210</a> %e A197278 Some solutions containing all values 0 to 4 for n=4: %e A197278 ..2..1..0..1..1..0....2..1..0..0..0..0....2..1..0..0..0..1....0..0..0..0..1..2 %e A197278 ..1..4..1..1..3..0....1..4..1..1..3..1....1..4..1..1..3..1....1..3..1..1..4..1 %e A197278 ..0..1..3..0..1..1....0..1..2..3..1..1....0..1..4..1..1..0....3..1..1..3..1..0 %e A197278 ..1..3..1..0..1..2....0..1..2..1..0..0....0..1..1..0..1..1....1..0..0..0..1..1 %Y A197278 Column 6 of A197280. %K A197278 nonn,changed %O A197278 1,1 %A A197278 _R. H. Hardin_, Oct 12 2011