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

Offset: 2

Author

Alois P. Heinz, Oct 18 2017

Keywords

• nonn

Links

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

Crossrefs

Column k=2 of A293113.

Cf. A000009, A293741.

Formula

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