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 A183480 #7 Jul 22 2025 08:59:28 %S A183480 23,1647,12131,270549,7773025,116198719,2519745049,56697667073, %T A183480 1077056431167,22884814320491,486391513434439,9923123962205421, %U A183480 208990562982405425,4391311455637955479,91402396553197281527 %N A183480 Number of nX6 0..2 arrays with every element equal to either the sum mod 3 of its vertical neighbors or the sum mod 3 of its horizontal neighbors. %C A183480 Column 6 of A183483 %H A183480 R. H. Hardin, <a href="/A183480/b183480.txt">Table of n, a(n) for n = 1..18</a> %e A183480 Some solutions for 4X6 %e A183480 ..0..2..2..0..1..1....0..0..0..0..1..1....0..1..1..2..1..2....0..0..0..0..0..1 %e A183480 ..0..0..0..0..0..0....0..0..0..0..2..0....0..1..1..0..2..2....0..0..0..0..0..1 %e A183480 ..0..0..0..0..1..0....1..2..1..0..1..2....0..2..2..0..0..0....1..0..2..2..0..0 %e A183480 ..0..1..1..0..1..0....1..2..1..0..2..2....0..0..0..0..1..1....1..0..2..2..0..0 %K A183480 nonn %O A183480 1,1 %A A183480 _R. H. Hardin_ Jan 05 2011