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Search: id:A114779
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| 1, 1, 2, 6, 24, 120, 1440, 30240, 967680, 43545600, 5225472000, 1207084032000, 463520268288000, 271159356948480000, 455547719673446400000, 1578472848668491776000000, 9698137182219213471744000000
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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Eric Weisstein's World of Mathematics, Multifactorial.
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FORMULA
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a(n) = Prod[i=0 to n] n!!!!. a(n) = Prod[i=0 to n] A007662(n). a(n) = n!!!! * a(n-1) where a(0) = 1, a(1) = 1 and n >= 2. a(n) = n*(n-4)!!!! * a(n-1) where a(0) = 1, a(1) = 1, a(2) = 2.
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EXAMPLE
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a(10) = 1!!!! * 2!!!! * 3!!!! * 4!!!! * 5!!!! * 6!!!! * 7!!!! * 8!!!! * 9!!!! * 10!!!! = 1 * 2 * 3 * 4 * 5 * 12 * 21 * 32 * 45 * 120 = 5225472000 = 2^13 * 3^6 * 5^3 * 7.
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CROSSREFS
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Cf. A006882, A007662, A000178, A114347.
Sequence in context: A079854 A024923 A037992 this_sequence A144167 A104983 A144251
Adjacent sequences: A114776 A114777 A114778 this_sequence A114780 A114781 A114782
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 18 2006
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