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Search: id:A103815
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| A103815 |
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Product[Fibonacci[k],{k,1,n}]-1. |
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+0
2
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| 0, 0, 1, 5, 29, 239, 3119, 65519, 2227679, 122522399, 10904493599, 1570247078399, 365867569267199, 137932073613734399, 84138564904377983999, 83044763560621070207999, 132622487406311849122175999
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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a(n) asymptotic to Phi^A000217(n). Prime for n = 4, 5, 6, 7, 8, 14, 15. Semiprime for n = 9, 10, 11, 20.
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FORMULA
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a(n) = Product[Fibonacci[k], {k, 1, n}]-1 = Product[A000045[k], {k, 1, n}]-1.
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EXAMPLE
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a(15) = 1 * 1 * 2 * 3 * 5 * 8 * 13 * 21 * 34 * 55 * 89 * 144 * 233 * 377 * 610 - 1 = 84138564904377983999 is prime.
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CROSSREFS
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Cf. A000045, A000217, A052449.
Sequence in context: A087662 A113012 A000354 this_sequence A134752 A112799 A020531
Adjacent sequences: A103812 A103813 A103814 this_sequence A103816 A103817 A103818
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Mar 29 2005
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