A240615 Number of n-length words w over a 9-ary alphabet such that w is empty or a prefix z concatenated with letter a_i and i=1 or 0 < #(z,a_{i-1}) >= #(z,a_i), where #(z,a_i) counts the occurrences of the i-th letter in z.

1, 1, 2, 5, 14, 46, 165, 651, 2771, 12638, 61397, 315507, 1708420, 9693168, 57360909, 352099643, 2229930365, 14494768448, 96229497555, 649761232948, 4446218110646, 30745322129155, 214353097904732, 1504152530715607, 10609439744527674, 75146372454242527

Offset

0,3

Links

Table of n, a(n) for n=0..25.

Crossrefs

Column k=9 of A240608.

Sequence in context: A240612 A240613 A240614 * A240616 A240617 A001680

Adjacent sequences: A240612 A240613 A240614 * A240616 A240617 A240618

Keyword

nonn

Author

Alois P. Heinz, Apr 09 2014

Status

approved