A009819 - OEIS

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A009819

tanh(tan(x)*tan(x))=2/2!*x^2+16/4!*x^4+32/6!*x^6-18944/8!*x^8...

%I #15 Apr 02 2017 21:13:04

%S 0,2,16,32,-18944,-2146048,-147605504,12359002112,9374161371136,

%T 2762835317030912,343159496128331776,-231213975915368808448,

%U -236417180330506147856384,-118337919812286157284179968

%N tanh(tan(x)*tan(x))=2/2!*x^2+16/4!*x^4+32/6!*x^6-18944/8!*x^8...

%t Tanh[ Tan[ x ]^2 ] (* Even Part *)

%K sign

%O 0,2

%A _R. H. Hardin_

%E Extended with signs by _Olivier Gérard_, Mar 15 1997