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Expansion of tanh(tanh(x)*tan(x)).
2

%I #7 Feb 24 2012 12:51:04

%S 2,-128,12032,365688832,-2002811158528,-67148259011330048,

%T 3766780331499896963072,40680896591210190242578432,

%U -72225295511520670153244114157568

%N Expansion of tanh(tanh(x)*tan(x)).

%e tanh(tanh(x)*tan(x))=2/2!*x^2-128/6!*x^6+12032/10!*x^10...

%t Tanh[ Tanh[ x ]*Tan[ x ] ] (* [ x^(4n+2) ] *)

%Y 2 * A009823(n).

%K sign

%O 0,1

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