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A007480
a(n) = denominator of sum_{k=1..n} k^(-4).
(Formerly M5028)
12
1, 16, 1296, 20736, 12960000, 12960000, 31116960000, 497871360000, 40327580160000, 40327580160000, 590436101122560000, 590436101122560000, 16863445484161436160000, 16863445484161436160000, 16863445484161436160000, 269815127746582978560000
OFFSET
1,2
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
D. Y. Savio, E. A. Lamagna and S.-M. Liu, Summation of harmonic numbers, pp. 12-20 of E. Kaltofen and S. M. Watt, editors, Computers and Mathematics, Springer-Verlag, NY, 1989.
FORMULA
a(n) = denominator of (Pi^4/90 - zeta(4, n+1)). - Arkadiusz Wesolowski, Nov 23 2012
Denominators of coefficients in expansion of PolyLog(4, x)/(1 - x). - Ilya Gutkovskiy, Apr 10 2017
MATHEMATICA
Denominator[Accumulate[1/Range[20]^4]] (* Harvey P. Dale, Dec 25 2013 *)
CROSSREFS
Cf. A007410.
Sequence in context: A334585 A163929 A072914 * A369169 A307814 A186420
KEYWORD
nonn,easy,frac
STATUS
approved