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 A213862 #7 Oct 31 2018 22:31:41 %S A213862 1,1,3,106,115955,7236515981,40684710729862072, %T A213862 29745278219128813035415595,3847028733161627562733350467148495403, %U A213862 114752550881830601773639529476205016572641397025904,996942995951678818059423286104073541295789338859855813183302036541 %N A213862 Number of words w where each letter of the n-ary alphabet occurs n times and for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z. %e A213862 a(0) = 1: the empty word. %e A213862 a(1) = 1: a. %e A213862 a(2) = 3: aabb, abab, baab. %e A213862 a(3) = 106: aaabbbccc, aaabbcbcc, aaabbccbc, ..., cbaababcc, cbaabacbc, cbaabcabc. %Y A213862 Main diagonal of A213275. %K A213862 nonn %O A213862 0,3 %A A213862 _Alois P. Heinz_, Jun 23 2012