Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #11 Aug 18 2014 13:52:27
%S 1,1,7,62,127,146,2828954,32764,16931177,11499383114,183092554714,
%T 13299018868,3965530936622474,88306001369044,260212136880609068,
%U 7400951287808330864888,16555640865486520478399,16179883156293315362,58334570685127434999731256122
%N Numerator of s_{2n}, where s_0 = 1, s_n = | 2^n*(2^(n-1)-1)*Bernoulli(n)/n! | for n>0.
%D F. Hirzebruch, Topological Methods in Algebraic Geometry, Springer, 3rd. ed., 1966; p. 12, Eq. 11.
%F G.f.: (x*sec(x)^2/tan(x))/2=sum{n>=0, a(n)*x^(2*n)} - _Vladimir Kruchinin_, Feb 04 2013
%F a(n) = numerator(Zeta(2*n)*(4^n-2)/Pi^(2*n)). - _Peter Luschny_, Aug 11 2014
%e 1, 1/3, 7/45, 62/945, 127/4725, 146/13365, 2828954/638512875, 32764/18243225, 16931177/23260111875, 11499383114/38979295480125, ...
%p A171078 := n -> numer(Zeta(2*n)*(4^n-2)/Pi^(2*n));
%p seq(A171078(n), n=0..18); # _Peter Luschny_, Aug 11 2014
%Y Cf. A171079 (denominators).
%K nonn,frac
%O 0,3
%A _N. J. A. Sloane_, Sep 06 2010