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A243476 Number of isoscent sequences of length n with exactly three descents. 2
10, 216, 2765, 27214, 227847, 1708700, 11832896, 77170252, 480381209, 2881934792, 16782041642, 95373448420, 531211249132, 2909490548577, 15712454516343, 83849134367589, 442957532385072, 2319975180476948, 12061609189508662, 62313958408668146, 320192732763382270 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,1

LINKS

Joerg Arndt and Alois P. Heinz, Table of n, a(n) for n = 7..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, 3]; Table[a[n], {n, 7, 40}] (* Jean-Fran├žois Alcover, Feb 09 2015, after A242352 *)

CROSSREFS

Column k=3 of A242352.

Sequence in context: A278125 A274763 A002967 * A305107 A294850 A259189

Adjacent sequences:  A243473 A243474 A243475 * A243477 A243478 A243479

KEYWORD

nonn

AUTHOR

Joerg Arndt and Alois P. Heinz, Jun 05 2014

STATUS

approved

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Last modified June 25 17:47 EDT 2019. Contains 324353 sequences. (Running on oeis4.)