%I M5050 #32 May 31 2022 03:28:10
%S 1,17,1393,22369,14001361,14011361,33654237761,538589354801,
%T 43631884298881,43635917056897,638913789210188977,638942263173398977,
%U 18249420414596570742097,18249859383918836502097,18250192489014819937873
%N Numerator of Sum_{k=1..4} k^(-4).
%C p divides a(p-1) for prime p > 5. p divides a((p-1)/2) for prime p > 5. p^2 divides a((p-1)/2) for prime p = 31, 37. - _Alexander Adamchuk_, Jul 07 2006
%C p^2 divides a(p-1) for prime p = 37. - _Alexander Adamchuk_, Nov 07 2006
%C Denominators are A007480. See the W. Lang link under A103345 for the rationals and more.
%C The limit of the rationals Zeta(n) := Sum_{k=1..n} 1/k^4 as n -> infinity is (Pi^4)/90, which is approximately 1.082323234. See A013662.
%D D. Y. Savio, E. A. Lamagna, and S.-M. Liu, Summation of harmonic numbers, pp. 12-20, in: E. Kaltofen and S. M. Watt, editors, Computers and Mathematics, Springer-Verlag, NY, 1989.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H T. D. Noe, <a href="/A007410/b007410.txt">Table of n, a(n) for n=1..200</a>
%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha103.htm">Factorizations of many number sequences</a>.
%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha1297.htm">Factorizations of many number sequences</a>.
%F Numerators of the coefficients in the expansion of PolyLog(4, x)/(1 - x). - _Ilya Gutkovskiy_, Apr 10 2017
%t Numerator[Table[Sum[1/k^4,{k,1,n}],{n,1,20}]] (* _Alexander Adamchuk_, Jul 07 2006 *)
%t Accumulate[1/Range[20]^4]//Numerator (* _Harvey P. Dale_, Jun 28 2020 *)
%o (PARI) a(n)=numerator(sum(k=1,n,1/k^4)) \\ _Charles R Greathouse IV_, Jul 19 2011
%Y Cf. A001008, A007406, A007408, A007480, A013662.
%K nonn,frac
%O 1,2
%A _N. J. A. Sloane_, _Mira Bernstein_