A243482 Number of isoscent sequences of length n with exactly nine descents.

1, 1842, 381540, 33260687, 1764436385, 67244544426, 2018462900473, 50530007996596, 1096301608172492, 21183116277395043, 371926458625987333, 6025302522233251390, 91147815762874899354, 1299862836761209689164, 17611186926254063273931, 228129250314546958924423

Offset

15,2

Links

Joerg Arndt and Alois P. Heinz, Table of n, a(n) for n = 15..100

Mathematica

b[n_, i_, t_] := b[n, i, t] = If[n < 1, 1, Expand[Sum[ If[j < i, x, 1] *b[n - 1, j, t + If[j == i, 1, 0]], {j, 0, t + 1}]]]; a[n_] := Coefficient[b[n - 1, 0, 0], x, 9]; Table[a[n], {n, 15, 40}] (* Jean-François Alcover, Feb 09 2015, after A242352 *)

Crossrefs

Column k=9 of A242352.

Sequence in context: A231079 A257319 A287172 * A252214 A112017 A297894

Adjacent sequences: A243479 A243480 A243481 * A243483 A243484 A243485

Keyword

nonn

Author

Joerg Arndt and Alois P. Heinz, Jun 05 2014

Status

approved