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 A264820 #9 Dec 23 2021 21:52:19 %S A264820 1,4,59,1644,83599,6680669,731477306 %N A264820 a(n) is the number of 3 X n arrays of permutations of 0..n*3-1 with rows nondecreasing modulo 3 and columns nondecreasing modulo 7. %C A264820 Row 3 of A264818. %e A264820 Some solutions for n=5: %e A264820 9 0 10 7 14 0 12 14 11 8 12 0 7 1 4 9 7 4 14 8 %e A264820 3 1 4 2 8 7 13 10 4 1 13 14 2 8 11 3 0 12 1 10 %e A264820 12 6 13 5 11 9 6 3 5 2 6 3 9 10 5 6 13 5 2 11 %Y A264820 Cf. A264818. %K A264820 nonn,more %O A264820 1,2 %A A264820 _R. H. Hardin_, Nov 25 2015