A012696 - OEIS

%I #4 Feb 24 2012 12:51:05

%S 2,-16,32,18944,-1904128,41160704,41418432512,-13226611572736,

%T 1026478445821952,1419327244545818624,-990157599155377143808,

%U 185269154824838954614784,314145305969818487050207232

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

%K sign

%O 0,1

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