Expansion of e.g.f. cos(tan(x))/exp(x).

Terms

a(0) =1a(1) =-1a(2) =0a(3) =2a(4) =-12a(5) =44a(6) =-216a(7) =944a(8) =-5296a(9) =27632a(10) =-168128a(11) =975072a(12) =-5391680a(13) =27882048a(14) =38412672a(15) =-1986004224a(16) =61881368832a(17) =-850359527680