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A123438
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Numbers n such that the denominator of n!/!n (= A000142(n)/A000166(n)) is prime.
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0
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4, 5, 6, 7, 10, 11, 15, 16, 34, 44, 63, 66, 168, 427, 575, 928, 1094, 1218, 1363, 1713
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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a[n_] := Sum[(-1)^k/k!, {k, 0, n}]; Select[Range[100], PrimeQ[Numerator[a[#]]] &] (* G. C. Greubel, Oct 31 2017 *)
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PROG
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(PARI) isok(n) = isprime(numerator(sum(k=0, n, (-1)^k/k!))); \\ Michel Marcus, Aug 28 2013
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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