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A135396 a(n) = Product_{d divides n} (n-d)!. 2
1, 1, 2, 12, 24, 17280, 720, 87091200, 29030400, 1755758592000, 3628800, 1525930675524002119680000000, 479001600, 15033074749223731200000, 151533393472175210496000000, 2201737050440244933006930739200000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..100

EXAMPLE

n=6, d(i)< 6 are 1;2;3; a(6)= (6-1)! * (6-2)! * (6-3)! = 17280

MAPLE

A135396 := proc(n) local dvs ; dvs := numtheory[divisors](n) minus {n} ; mul( (n-i)!, i=dvs) ; end: seq(A135396(n), n=1..30) ; # R. J. Mathar, Feb 19 2008

MATHEMATICA

Table[Product[(n - Divisors[n][[i]])!, {i, 1, Length[Divisors[n]]}], {n, 1, 20}] (* Stefan Steinerberger, Feb 19 2008 *)

Table[Times@@((n-Divisors[n])!), {n, 20}] (* Harvey P. Dale, Dec 10 2014 *)

PROG

(PARI) a(n)=my(s=1); fordiv(n, d, s*=(n-d)!); s \\ Charles R Greathouse IV, Oct 12 2016

CROSSREFS

Cf. A000142.

Sequence in context: A232248 A091137 A092825 * A031048 A294554 A098707

Adjacent sequences:  A135393 A135394 A135395 * A135397 A135398 A135399

KEYWORD

easy,nonn

AUTHOR

Ctibor O. Zizka, Feb 17 2008

EXTENSIONS

Definition simplified by Stefan Steinerberger, Feb 19 2008

More terms from R. J. Mathar and Stefan Steinerberger, Feb 19 2008

STATUS

approved

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Last modified October 18 07:19 EDT 2019. Contains 328146 sequences. (Running on oeis4.)