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A007480 a(n) = denominator of sum_{k=1..n} k^(-4).
(Formerly M5028)
11
1, 16, 1296, 20736, 12960000, 12960000, 31116960000, 497871360000, 40327580160000, 40327580160000, 590436101122560000, 590436101122560000, 16863445484161436160000, 16863445484161436160000, 16863445484161436160000, 269815127746582978560000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

T. D. Noe, Table of n, a(n) for n=1..200

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: A248619 A163929 A072914 * A186420 A163395 A134375

Adjacent sequences:  A007477 A007478 A007479 * A007481 A007482 A007483

KEYWORD

nonn,easy,frac

AUTHOR

N. J. A. Sloane, Mira Bernstein

STATUS

approved

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Last modified February 20 22:51 EST 2019. Contains 320362 sequences. (Running on oeis4.)