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 A265453 #4 Dec 09 2015 09:58:28 %S A265453 12,250,7422,216466,6056182,161435322,4148236142,103476193518, %T A265453 2523840866186,60444664118334,1426665304637082,33267668122964462, %U A265453 768000220549574982,17579038730691587714,399459371232734669014 %N A265453 Number of nX3 0..n+3-2 arrays with each element differing from its horizontal and vertical neighbors by one or two. %C A265453 Column 3 of A265458. %H A265453 R. H. Hardin, <a href="/A265453/b265453.txt">Table of n, a(n) for n = 1..210</a> %e A265453 Some solutions for n=3 %e A265453 ..3..2..0....1..2..0....4..2..0....1..3..1....0..2..3....2..3..2....3..1..0 %e A265453 ..1..0..2....0..1..2....2..3..1....2..4..3....2..0..1....0..2..3....2..3..1 %e A265453 ..2..1..3....1..2..4....3..1..0....4..3..4....3..2..3....1..0..1....3..4..2 %Y A265453 Cf. A265458. %K A265453 nonn %O A265453 1,1 %A A265453 _R. H. Hardin_, Dec 09 2015