Expansion of cosh(tan(x))/exp(x).

Terms

a(0) =1a(1) =-1a(2) =2a(3) =-4a(4) =16a(5) =-56a(6) =328a(7) =-1576a(8) =11712a(9) =-70912a(10) =638720a(11) =-4668544a(12) =49459840a(13) =-423673472a(14) =5159926528a(15) =-50674728448a(16) =697030680576