A216443 a(n) = n!! mod !n.

0, 1, 8, 15, 48, 105, 384, 945, 3840, 10395, 46080, 135135, 645120, 2027025, 10321920, 34459425, 185794560, 654729075, 3715891200, 13749310575, 81749606400, 316234143225, 1961990553600, 7905853580625, 51011754393600, 213458046676875, 1428329123020800

Offset

2,3

Comments

!n is a subfactorial number (A000166).

n!! is a double factorial number (A006882).

Links

Indranil Ghosh, Table of n, a(n) for n = 2..800

Example

a(5) = 5!! mod !5 = 15 mod 44 = 15. - Indranil Ghosh, Feb 15 2017

Mathematica

Table[Mod[n !!, Subfactorial[n]], {n, 2, 100} ]

Crossrefs

Cf. A006882, A000166.

Sequence in context: A341117 A255428 A367876 * A331463 A362906 A350442

Adjacent sequences: A216440 A216441 A216442 * A216444 A216445 A216446

Keyword

nonn

Author

Michel Lagneau, Sep 07 2012

Status

approved