0,2

tan(tan(x)*tan(x))=2/2!*x^2+16/4!*x^4+512/6!*x^6+34816/8!*x^8...

Tan[ Tan[ x ]^2 ] (* Even Part *)

Sequence in context: A140310 A140311 A012389 this_sequence A012393 A063387 A063391

Adjacent sequences: A009707 A009708 A009709 this_sequence A009711 A009712 A009713

nonn

R. H. Hardin (rhhardin(AT)att.net)

Extended and signs tested Mar 15 1997 by Olivier Gerard.