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 A268424 #4 Feb 04 2016 09:54:36 %S A268424 14,2530,467899,92967597,17282463434,3197637400309,577216284723410, %T A268424 103129350712869051,18199468798597838146,3185845262388985273409, %U A268424 553601961042772734126748,95663189554686667773844253 %N A268424 Number of 4Xn 0..3 arrays with every repeated value in every row unequal to the previous repeated value, and in every column equal to the previous repeated value, and new values introduced in row-major sequential order. %C A268424 Row 4 of A268423. %H A268424 R. H. Hardin, <a href="/A268424/b268424.txt">Table of n, a(n) for n = 1..41</a> %e A268424 Some solutions for n=2 %e A268424 ..0..1....0..1....0..1....0..1....0..1....0..0....0..0....0..1....0..0....0..1 %e A268424 ..2..3....0..2....2..0....2..2....0..2....1..0....1..0....2..3....1..2....2..1 %e A268424 ..2..2....0..0....2..0....2..2....2..2....2..3....0..2....0..1....3..0....0..0 %e A268424 ..2..3....2..1....0..3....3..0....0..3....2..1....2..3....0..3....1..1....3..2 %Y A268424 Cf. A268423. %K A268424 nonn %O A268424 1,1 %A A268424 _R. H. Hardin_, Feb 04 2016