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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, 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
CROSSREFS
Column k=9 of A240608.
Sequence in context: A240612 A240613 A240614 * A240616 A240617 A001680
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Apr 09 2014
STATUS
approved