%I #4 Feb 24 2012 12:51:09
%S 1,0,20,-280,18000,-1277760,159922880,-26119949440,5923118588160,
%T -1705199348152320,619341836139299840,-274598298613483878400,
%U 146431095418622106193920,-92305017354779154307399680
%N arcsinh(sec(x)*tanh(x))=x+20/5!*x^5-280/7!*x^7+18000/9!*x^9...
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)