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 A267630 #6 Aug 12 2016 06:54:01 %S A267630 6,27,208,2386,32208,445970,6039160,80742586,1086798652,14898269746, %T A267630 208430268352,2964609577834,42639468240764,617605254789776, %U A267630 8990677585470960,131473208822453124,1931423573382740480 %N A267630 Number of 4Xn arrays containing n copies of 0..4-1 with every element equal to or 1 greater than any west neighbor modulo 4 and the upper left element equal to 0. %C A267630 Row 4 of A267629. %H A267630 R. H. Hardin, <a href="/A267630/b267630.txt">Table of n, a(n) for n = 1..21</a> %e A267630 Some solutions for n=4 %e A267630 ..0..1..1..2....0..0..0..0....0..0..1..1....0..1..2..2....0..0..0..1 %e A267630 ..3..3..3..0....1..1..2..2....2..3..0..1....0..1..2..3....0..1..1..2 %e A267630 ..0..0..1..2....1..1..2..2....2..2..3..3....3..0..1..2....1..2..3..3 %e A267630 ..1..2..2..3....3..3..3..3....0..1..2..3....3..3..0..1....2..2..3..3 %Y A267630 Cf. A267629. %K A267630 nonn %O A267630 1,1 %A A267630 _R. H. Hardin_, Jan 18 2016