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 A267909 #4 Jan 22 2016 07:58:50 %S A267909 29,5046,878004,104491831,10441322974,922017784240,74691010105571, %T A267909 5680483902454184,411946383314752314,28803298484312712803, %U A267909 1957402980977660239136,130069621243447882741372 %N A267909 Number of nX5 0..2 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 A267909 Column 5 of A267911. %H A267909 R. H. Hardin, <a href="/A267909/b267909.txt">Table of n, a(n) for n = 1..48</a> %e A267909 Some solutions for n=2 %e A267909 ..0..0..1..2..2....0..1..1..0..2....0..1..0..2..2....0..1..2..2..0 %e A267909 ..1..2..1..2..0....1..2..2..1..1....2..0..2..0..1....0..1..2..2..1 %Y A267909 Cf. A267911. %K A267909 nonn %O A267909 1,1 %A A267909 _R. H. Hardin_, Jan 22 2016