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A276487
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Denominator of Sum_{k=1..n} 1/k^n.
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3
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1, 4, 216, 20736, 777600000, 46656000000, 768464444160000000, 247875891108249600000000, 4098310578334288576512000000000, 413109706296096288512409600000000, 7425496288284402957501110551810198732800000000000
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OFFSET
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1,2
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COMMENTS
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Also denominator of zeta(n) - Hurwitz zeta(n,n+1), where zeta(s) is the Riemann zeta function and Hurwitz zeta(s,a) is the Hurwitz zeta function.
Sum_{k>=1} 1/k^n = zeta(n).
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LINKS
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EXAMPLE
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1, 5/4, 251/216, 22369/20736, 806108207/777600000, 47464376609/46656000000, 774879868932307123/768464444160000000, ...
a(3) = 216, because 1/1^3 + 1/2^3 + 1/3^3 = 251/216.
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MAPLE
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MATHEMATICA
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Table[Denominator[HarmonicNumber[n, n]], {n, 1, 11}]
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PROG
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(PARI) a(n) = denominator(sum(k=1, n, 1/k^n)); \\ Michel Marcus, Sep 06 2016
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CROSSREFS
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KEYWORD
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nonn,frac
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AUTHOR
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STATUS
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approved
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