A225964 Number of permutations of [n] having exactly 3 strong fixed blocks.

1, 9, 63, 419, 2868, 20932, 165662, 1432746, 13578086, 140951642, 1598792812, 19739303596, 264041415799, 3807692229035, 58907522237037, 973166134330293, 17094936849558000, 318092941562300736, 6248389843759774380, 129180041710223480596, 2803277432655658573548

Offset: 7

Author

Alois P. Heinz, May 22 2013

Keywords

• nonn

Comments

See A186373 for the definition of strong fixed blocks.

Links

• Alois P. Heinz, Table of n, a(n) for n = 7..450

Crossrefs

Column k=3 of A186373.

Formula

a(n) ~ 2 * n! / n^5. - Vaclav Kotesovec, Aug 29 2014