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A216443 a(n) = n!! mod !n. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A275277 A341117 A255428 * A331463 A151792 A243295

Adjacent sequences:  A216440 A216441 A216442 * A216444 A216445 A216446

KEYWORD

nonn

AUTHOR

Michel Lagneau, Sep 07 2012

STATUS

approved

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Last modified July 28 17:07 EDT 2021. Contains 346335 sequences. (Running on oeis4.)