A293883 - OEIS

A293883

Number of sets of nonempty words with a total of n letters over binary alphabet containing the second 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, 3, 8, 20, 47, 106, 237, 522, 1146, 2485, 5406, 11644, 25157, 53964, 116003, 247987, 530999, 1131889, 2415431, 5135838, 10927816, 23182209, 49199697, 104154808, 220543306, 465996956, 984704338, 2076988457, 4380764354, 9225209588, 19424813915, 40844509107

(list; graph; refs; listen; history; text; internal format)

OFFSET

2,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 2..1000

FORMULA

a(n) = A293741(n) - A000009(n).

CROSSREFS

Column k=2 of A293113.

Cf. A000009, A293741.

Sequence in context: A048492 A006776 A291097 * A050231 A136305 A284943

Adjacent sequences: A293880 A293881 A293882 * A293884 A293885 A293886

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 18 2017

STATUS

approved