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Coefficient of [x^(4*n+2)] in e.g.f. tan(cosh(x) - cos(x)).
0

%I #14 Aug 07 2018 03:32:15

%S 2,242,493922,4867022162,146803464634562,10586916198380287922,

%T 1560405836504795306526242,421594801591208996367201480722,

%U 192759827198349576131799688610789762

%N Coefficient of [x^(4*n+2)] in e.g.f. tan(cosh(x) - cos(x)).

%e (2/2!)*x^2 + (242/6!)*x^6 + (493922/10!)*x^10 + (4867022162/14!)*x^14 + ...

%p g := taylor(tan(cos(x)-cosh(x)),x=0,100):q := seq(abs(coeff(g,x,4*i+2)*(4*i+2)!),i=0..12);

%K nonn

%O 0,1

%A Patrick Demichel (patrick.demichel(AT)hp.com)

%E More terms from _Sascha Kurz_, Mar 24 2002

%E Missing a(0)=2 inserted and title improved by _Sean A. Irvine_, Aug 06 2018