A241796 Number of ballot sequences of length n having exactly three descents.

1, 17, 145, 836, 3846, 15002, 52132, 164576, 484609, 1337597, 3521517, 8850458, 21485321, 50358968, 114911640, 255114977, 554333346, 1178070741, 2459840199, 5042845917, 10185374250, 20257833206, 39778823250, 77088115856, 147739793527, 279923493220

Offset

6,2

Links

Table of n, a(n) for n=6..31.

Example

a(6) = 1: [1,2,1,3,2,1].

Crossrefs

Column k=3 of A238121 and of A238122.

Sequence in context: A163038 A216422 A008417 * A181908 A233328 A364155

Adjacent sequences: A241793 A241794 A241795 * A241797 A241798 A241799

Keyword

nonn

Author

Joerg Arndt and Alois P. Heinz, Apr 28 2014

Status

approved