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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.
2
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
4,2
LINKS
FORMULA
a(n) = A293743(n) - A293742(n).
CROSSREFS
Column k=4 of A293113.
Sequence in context: A224415 A255459 A083877 * A209836 A272762 A245551
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Oct 18 2017
STATUS
approved