This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A007409 M4579 #22 May 15 2018 13:29:16
%S A007409 1,8,216,1728,216000,24000,8232000,65856000,16003008000,16003008000,
%T A007409 21300003648000,21300003648000,46796108014656000,46796108014656000,
%U A007409 46796108014656000,374368864117248000,1839274229408039424000
%N A007409 Denominators of Sum_{k=1..n} 1/k^3.
%C A007409 Largest prime factor in A007409(n) (n > 1) is A007917(n), occurring always to the power 3. - _M. F. Hasler_, Nov 10 2006
%D A007409 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.
%D A007409 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A007409 T. D. Noe, <a href="/A007409/b007409.txt">Table of n, a(n) for n=1..200</a>
%p A007409 A007409:= n->denom(sum(1/k^3,k=1..n)); # _M. F. Hasler_, Nov 10 2006
%t A007409 Table[Denominator[Sum[1/k^3, {k, n}]], {n, 10}] (* _Alonso del Arte_, Dec 30 2012 *)
%Y A007409 Cf. A007408, A007917.
%K A007409 nonn,easy,frac
%O A007409 1,2
%A A007409 _N. J. A. Sloane_, _Mira Bernstein_