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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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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
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OFFSET
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1,3
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COMMENTS
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LINKS
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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, Aug 15 2007
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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