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 A268010 #4 Jan 24 2016 09:27:53 %S A268010 1,2,4,12,40,154,656,3074,15616,85360,498464,3092450,20286360, %T A268010 140153382,1016262080,7710988372,61062381784,503482376930, %U A268010 4313580705728,38328590370762,352618807559008,3353663977088848,32927374589861296 %N A268010 Number of 1Xn 0..n arrays with every repeated value in every row and column unequal to the previous repeated value, and new values introduced in row-major sequential order. %C A268010 Row 1 of A268009. %H A268010 R. H. Hardin, <a href="/A268010/b268010.txt">Table of n, a(n) for n = 1..122</a> %e A268010 Some solutions for n=8 %e A268010 ..0..1..0..1..0..2..0..0....0..1..1..2..3..4..2..1....0..1..2..3..0..2..4..3 %Y A268010 Cf. A268009. %K A268010 nonn %O A268010 1,2 %A A268010 _R. H. Hardin_, Jan 24 2016