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Search: id:A114790
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| 1, 1, 2, 6, 24, 120, 720, 10080, 241920, 8709120, 435456000, 28740096000, 4828336128000, 1506440871936000, 759246199455744000, 569434649591808000000, 601322989968949248000000
(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] n!5. a(n) = Prod[i=0 to n] A085157(n). a(n) = n!!!!! * a(n-1) where a(0) = 1, a(1) = 1 and n >= 2. a(n) = n*(n-5)!!!!! * 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 * 6 * 14 * 24 * 36 * 50 = 435456000 = 2^11 * 3^5 * 5^3 * 7.
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CROSSREFS
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Cf. A006882, A007662, A085157, A000178, A114347.
Sequence in context: A130641 A129655 A114796 this_sequence A079854 A024923 A037992
Adjacent sequences: A114787 A114788 A114789 this_sequence A114791 A114792 A114793
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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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