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Search: id:A114806
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| A114806 |
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Nonuple factorial, 9-factorial, n!9, n!!!!!!!!!. |
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+0
2
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| 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 22, 36, 52, 70, 90, 112, 136, 162, 190, 440, 756, 1144, 1610, 2160, 2800, 3536, 4374, 5320, 12760, 22680, 35464, 51520, 71280, 95200, 123760, 157464, 196840, 484880, 884520, 1418560, 2112320, 2993760, 4093600
(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) = 1 for n<1, else a(n) = n*a(n-9).
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EXAMPLE
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a(10) = 10 * a(10-9) = 10 * a(1) = 10 * 1 = 10.
a(20) = 20 * a(20-9) = 20 * a(11) = 20 * (11*a(11-9)) = 20 * 11 * a(2) = 20 * 11 * 2 = 440.
a(30) = 30 * a(30-9) = 30 * a(21) = 30 * (21*a(21-9)) = 30 * 21 * a(12) = 30 * 21 * (12*a(12-9)) = 30 * 21 * 12 * 3 = 22680.
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CROSSREFS
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Cf. A000142, A006882, A007661, A007662, A085157, A085158.
Sequence in context: A116069 A081511 A030283 this_sequence A039229 A054659 A120125
Adjacent sequences: A114803 A114804 A114805 this_sequence A114807 A114808 A114809
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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 19 2006
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