A228671 - OEIS

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

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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.