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 A213291 #6 Jun 15 2012 03:52:01
%S A213291 1,3,9,18,36,74,165,367,869,2074,5168,13026,33749,88368,235389,632324,
%T A213291 1717202,4693604,12921864,35751336,99416633,277527448,777659128,
%U A213291 2185854247,6162168724,17416305904,49342480077,140094014788,398558682310,1135962971848
%N A213291 Number of n-length words w over ternary alphabet such that 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.
%H A213291 Alois P. Heinz, <a href="/A213291/b213291.txt">Table of n, a(n) for n = 0..200</a>
%e A213291 a(0) = 1: the empty word.
%e A213291 a(1) = 3: a, b, c for alphabet {a,b,c}.
%e A213291 a(2) = 9: aa, ab, ac, ba, bb, bc, ca, cb, cc.
%e A213291 a(3) = 18: aaa, aab, aac, aba, abc, aca, acb, baa, bac, bbb, bbc, bca, bcb, caa, cab, cba, cbb, ccc.
%Y A213291 Column k=3 of A213276.
%K A213291 nonn
%O A213291 0,2
%A A213291 _Alois P. Heinz_, Jun 08 2012