The OEIS is supported by the many generous donors to the OEIS Foundation.
%I #4 Feb 24 2012 12:50:36
%S 1,1,9,153,2993,-72111,-33331719,-7328604631,-1581635839519,
%T -356792088521439,-81022312424248727,-15576441107086727111,
%U 22243831754082386577,3229505766853670411015281
%N sec(sin(tan(x)))=1+1/2!*x^2+9/4!*x^4+153/6!*x^6+2993/8!*x^8...
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)