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A241630 Number of compositions of n with exactly five descents. 3
8, 73, 429, 1945, 7465, 25317, 78068, 222963, 597644, 1518370, 3683950, 8586866, 19320391, 42127208, 89307361, 184578961, 372786467, 737212357, 1429992711, 2724852920, 5107392644, 9427895421, 17157142969, 30810379849, 54643242181, 95783964110, 166059755226 (list; graph; refs; listen; history; text; internal format)
OFFSET

15,1

LINKS

Joerg Arndt and Alois P. Heinz, Table of n, a(n) for n = 15..1000

EXAMPLE

a(15) = 8: [3,2,1,2,1,3,2,1], [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], [2,1,3,2,1,2,1,2,1], [3,2,1,2,1,2,1,2,1], [2,1,2,1,2,1,3,2,1], [2,1,2,1,2,1,2,1,2,1].

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, 6), polynom))

end:

a:= n-> coeff(b(n, 0), x, 5):

seq(a(n), n=15..50);

MATHEMATICA

k = 5;

b[n_, i_] := b[n, i] = If[n == 0, 1, Sum[b[n - j, j]*

If[j < i, x, 1], {j, n}] + O[x]^(k + 1)];

a[n_] := SeriesCoefficient[b[n, 0], {x, 0, k}];

a /@ Range[15, 50] (* Jean-François Alcover, Aug 27 2021, after Maple code *)

CROSSREFS

Column k=5 of A238343 and of A238344.

Sequence in context: A058068 A096873 A282786 * A153482 A014991 A015577

Adjacent sequences: A241627 A241628 A241629 * A241631 A241632 A241633

KEYWORD

nonn

AUTHOR

Joerg Arndt and Alois P. Heinz, Apr 26 2014

STATUS

approved

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Last modified March 24 09:16 EDT 2023. Contains 361470 sequences. (Running on oeis4.)