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Search: id:A109915
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| A109915 |
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Product of all composite numbers k such that n<k<prime(r) where prime(r-1)<=n, or 1 if this set of k is empty. |
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+0
2
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| 1, 1, 4, 1, 6, 1, 720, 90, 10, 1, 12, 1, 3360, 240, 16, 1, 18, 1, 9240, 462, 22, 1, 11793600, 491400, 19656, 756, 28, 1, 30, 1, 45239040, 1413720, 42840, 1260, 36, 1, 59280, 1560, 40, 1, 42, 1, 91080, 2070, 46, 1, 311875200, 6497400, 132600, 2652
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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All terms that differ from 1 have the format A092435(i+1)/A092435(i). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 15 2007
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EXAMPLE
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a(7) = 8*9*10 =720.
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MAPLE
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A109915 := proc(n) local a, rm1, k; a := 1: rm1 := numtheory[pi](n) ; for k from n+1 to ithprime(rm1+1) do if not isprime(k) then a := a*k; fi; od: RETURN(a) ; end: seq(A109915(n), n=1..50) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 15 2007
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CROSSREFS
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Cf. A109914.
Sequence in context: A032145 A032050 A057160 this_sequence A098987 A153017 A038457
Adjacent sequences: A109912 A109913 A109914 this_sequence A109916 A109917 A109918
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jul 16 2005
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EXTENSIONS
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Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 15 2007
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