A243480 Number of isoscent sequences of length n with exactly seven descents.

130, 18196, 1027497, 35855578, 920132845, 19024724767, 334824869566, 5199938158961, 73073359931844, 946309985456857, 11449696018832655, 130815643776548834, 1423250326223813866, 14845562100052915605, 149281547622659687547, 1453772869428542126084

Offset

13,1

Links

Joerg Arndt and Alois P. Heinz, Table of n, a(n) for n = 13..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, 7]; Table[a[n], {n, 13, 40}] (* Jean-François Alcover, Feb 09 2015, after A242352 *)

Crossrefs

Column k=7 of A242352.

Sequence in context: A223846 A223872 A223797 * A223662 A224112 A184283

Adjacent sequences: A243477 A243478 A243479 * A243481 A243482 A243483

Keyword

nonn

Author

Joerg Arndt and Alois P. Heinz, Jun 05 2014

Status

approved