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A157625
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Product of the composite numbers between n+1 and 2n, both inclusive.
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3
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1, 4, 24, 48, 4320, 8640, 120960, 3628800, 7257600, 14515200, 6706022400, 13412044800, 8717829120000, 470762772480000, 941525544960000, 1883051089920000, 2112783322890240000, 147894832602316800000
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OFFSET
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1,2
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COMMENTS
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This function is very useful in a problem due to Paul Erdős recorded in A157017. - M. F. Hasler, Feb 26 2014
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LINKS
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FORMULA
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MATHEMATICA
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nn=20; With[{comps=Complement[Range[2nn], Prime[Range[PrimePi[2nn]]]]}, Table[ Times@@ Select[comps, #>n&&#<=2n&], {n, nn}]] (* Harvey P. Dale, Feb 18 2013 *)
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PROG
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(PARI) a(n)=prod(i=n+1, 2*n, if(isprime(i), 1, i))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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