A228671 Number of permutations of [n] having a shortest ascending run of length 4.

1, 0, 0, 0, 69, 250, 418, 658, 34649, 266267, 1369372, 5082045, 76637635, 876858377, 7147459470, 47396097511, 552146011437, 7418289082402, 82776784289657, 769968963165506, 9270154198456497, 136873296441831662, 1900983368776814542, 22997984983317347728

Offset

4,5

Links

Alois P. Heinz and Vaclav Kotesovec, Table of n, a(n) for n = 4..400 (first 100 terms from Alois P. Heinz)

Formula

a(n) ~ c * d^n * n!, where d = 0.50498188279961731119..., c = 0.223130847130100218... . - Vaclav Kotesovec, Sep 07 2014

Example

T(4) = 1: 1234.
T(8) = 69: 12354678, 12364578, ..., 46781235, 56781234.

Crossrefs

Column k=4 of A064315.

Sequence in context: A283053 A249899 A009434 * A115920 A183447 A296126

Adjacent sequences: A228668 A228669 A228670 * A228672 A228673 A228674

Keyword

nonn

Author

Alois P. Heinz, Aug 29 2013

Status

approved