A293885 Number of sets of nonempty words with a total of n letters over quaternary alphabet containing the fourth letter such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.

1, 5, 25, 102, 410, 1545, 5784, 21015, 76248, 272377, 974208, 3455177, 12287351, 43502174, 154554897, 547955950, 1950335934, 6937352521, 24777223885, 88515560121, 317513893877, 1139848959317, 4108296484542, 14823490668322, 53689879422115, 194704264528116

Offset: 4

Author

Alois P. Heinz, Oct 18 2017

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 4..1000

Crossrefs

Column k=4 of A293113.

Cf. A293742, A293743.

Formula

a(n) = A293743(n) - A293742(n).