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Search: id:A135396
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| A135396 |
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a(n) = product_{d divides n} (n-d)!. |
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+0
1
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| 1, 1, 2, 12, 24, 17280, 720, 87091200, 29030400, 1755758592000, 3628800, 1525930675524002119680000000, 479001600, 15033074749223731200000, 151533393472175210496000000, 2201737050440244933006930739200000000
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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n=6, d(i)< 6 are 1;2;3; a(6)= (6-1)! * (6-2)! * (6-3)! = 17280
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MAPLE
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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 (mathar(AT)strw.leidenuniv.nl), Feb 19 2008
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MATHEMATICA
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Table[Product[(n - Divisors[n][[i]])!, {i, 1, Length[Divisors[n]]}], {n, 1, 20}] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 19 2008
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CROSSREFS
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Cf. A000142.
Sequence in context: A002207 A091137 A092825 this_sequence A031048 A098707 A152811
Adjacent sequences: A135393 A135394 A135395 this_sequence A135397 A135398 A135399
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KEYWORD
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easy,nonn
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AUTHOR
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Ctibor O. ZIZKA (ctibor.zizka(AT)seznam.cz), Feb 17 2008
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EXTENSIONS
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Definition simplified by Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 19 2008
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl) and Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Feb 19 2008
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