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A241632 Number of compositions of n with exactly seven descents. 3
21, 259, 1932, 10898, 51083, 208936, 768594, 2594957, 8158005, 24140097, 67794864, 181889780, 468678716, 1164905882, 2803070038, 6549961919, 14901997455, 33085162997, 71822232573, 152710556875, 318509850193, 652536555773, 1314728710475, 2607856668543 (list; graph; refs; listen; history; text; internal format)
OFFSET

21,1

LINKS

Joerg Arndt and Alois P. Heinz, Table of n, a(n) for n = 21..1000

EXAMPLE

a(21) = 21: [3,2,1,2,1,3,2,1,3,2,1], [3,2,1,3,2,1,2,1,3,2,1], [3,2,1,3,2,1,3,2,1,2,1], [2,1,3,2,1,3,2,1,3,2,1], [2,1,2,1,2,1,3,2,1,3,2,1], [3,2,1,3,2,1,2,1,2,1,2,1], [2,1,2,1,3,2,1,2,1,3,2,1], [2,1,3,2,1,2,1,3,2,1,2,1], [3,2,1,2,1,3,2,1,2,1,2,1], [3,2,1,2,1,2,1,2,1,3,2,1], [2,1,3,2,1,2,1,2,1,3,2,1], [3,2,1,2,1,2,1,3,2,1,2,1], [2,1,2,1,3,2,1,3,2,1,2,1], [2,1,3,2,1,3,2,1,2,1,2,1], [3,2,1,2,1,2,1,2,1,2,1,2,1], [2,1,2,1,2,1,2,1,2,1,3,2,1], [2,1,3,2,1,2,1,2,1,2,1,2,1], [2,1,2,1,2,1,2,1,3,2,1,2,1], [2,1,2,1,2,1,3,2,1,2,1,2,1], [2,1,2,1,3,2,1,2,1,2,1,2,1], [2,1,2,1,2,1,2,1,2,1,2,1,2,1].

MAPLE

b:= proc(n, i) option remember;

      `if`(n=0, 1, convert(series(add(b(n-j, j)*

      `if`(j<i, x, 1), j=1..n), x, 8), polynom))

    end:

a:= n-> coeff(b(n, 0), x, 7):

seq(a(n), n=21..50);

CROSSREFS

Column k=7 of A238343 and of A238344.

Sequence in context: A022649 A165094 A322500 * A323972 A125433 A135122

Adjacent sequences:  A241629 A241630 A241631 * A241633 A241634 A241635

KEYWORD

nonn

AUTHOR

Joerg Arndt and Alois P. Heinz, Apr 26 2014

STATUS

approved

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Last modified May 26 04:46 EDT 2019. Contains 323579 sequences. (Running on oeis4.)