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 A267663 #6 May 04 2021 16:01:48 %S A267663 5,50,500,3143,18432,98438,508681,2560344,12721832,62688891,307514468, %T A267663 1504686646,7352965785,35912894408,175383062746,856630710989, %U A267663 4185293733440,20456112775414,100023287817835,489294036823648 %N A267663 Number of n X 4 0..1 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 A267663 Column 4 of A267667. %H A267663 R. H. Hardin, <a href="/A267663/b267663.txt">Table of n, a(n) for n = 1..210</a> %H A267663 R. H. Hardin, <a href="/A267663/a267663.txt">Empirical recurrence of order 80</a> %F A267663 Empirical recurrence of order 80 (see link above). %e A267663 Some solutions for n=6 %e A267663 ..0..1..0..0....0..0..1..1....0..1..0..0....0..1..0..0....0..0..1..0 %e A267663 ..0..1..0..0....1..0..1..0....0..1..1..0....1..0..0..1....1..0..1..1 %e A267663 ..0..1..0..0....1..0..1..1....1..0..1..0....1..1..0..0....0..1..1..0 %e A267663 ..0..0..1..0....1..1..0..1....0..1..0..0....0..1..0..1....1..0..1..1 %e A267663 ..1..1..0..1....0..0..1..1....0..0..1..0....1..1..0..1....1..0..1..0 %e A267663 ..0..1..1..0....1..0..0..1....0..1..0..0....0..0..1..1....1..1..0..1 %Y A267663 Cf. A267667. %K A267663 nonn %O A267663 1,1 %A A267663 _R. H. Hardin_, Jan 19 2016