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A216152
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A205957(n) where n is a nonprime number.
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2
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1, 2, 12, 48, 144, 1440, 34560, 483840, 7257600, 58060800, 3135283200, 125411328000, 2633637888000, 57940033536000, 5562243219456000, 27811216097280000, 723091618529280000, 6507824566763520000, 364438175738757120000, 327994358164881408000000
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OFFSET
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1,2
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COMMENTS
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a(1),...,a(10) are highly totient numbers (A097942) and products of distinct factorials (A058295). The author conjectures that this is true in general.
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LINKS
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FORMULA
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MATHEMATICA
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A205957[n_] := Exp[-Sum[MoebiusMu[p] Log[k/p], {k, 1, n}, {p, FactorInteger[k][[All, 1]]}]];
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PROG
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(Sage)
# sorted(list(set([A205957(n) for n in (0..31)])))
C = filter(lambda k: not is_prime(k), (1..n))
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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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