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A370581
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a(n) = n! * Sum_{d|n} d/(d! * (n/d)!).
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1
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1, 3, 4, 17, 6, 307, 8, 5049, 30250, 105851, 12, 25945933, 14, 77837775, 14529715216, 147891744017, 18, 13435316294419, 20, 7606841430988821, 16895152834560022, 183030822374423, 24, 387276381308571955225, 5385836820601036800026, 485735643993600027
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OFFSET
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1,2
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LINKS
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FORMULA
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If p is prime, a(p) = 1 + p.
E.g.f.: Sum_{k>0} x^k/k! * exp(x^k).
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PROG
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(PARI) a(n) = n!*sumdiv(n, d, d/(d!*(n/d)!));
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(sum(k=1, N, x^k/k!*exp(x^k))))
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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