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 A293884 #4 Oct 18 2017 19:19:06 %S A293884 1,4,16,53,173,532,1615,4785,14066,40908,118438,341253,981200,2815762, %T A293884 8075265,23149097,66373778,190376443,546401592,1569387414,4511532695, %U A293884 12980998062,37385342522,107771434819,310967929569,898108427259,2596180252466,7511411442182 %N A293884 Number of sets of nonempty words with a total of n letters over ternary alphabet containing the third letter such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter. %H A293884 Alois P. Heinz, <a href="/A293884/b293884.txt">Table of n, a(n) for n = 3..1000</a> %F A293884 a(n) = A293742(n) - A293741(n). %Y A293884 Column k=3 of A293113. %Y A293884 Cf. A293741, A293742. %K A293884 nonn %O A293884 3,2 %A A293884 _Alois P. Heinz_, Oct 18 2017