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

Terms

a(0) =1a(1) =-1a(2) =2a(3) =-6a(4) =16a(5) =-72a(6) =328a(7) =-1848a(8) =11712a(9) =-81088a(10) =638720a(11) =-5318016a(12) =49459840a(13) =-483162240a(14) =5159926528a(15) =-57865303296a(16) =697030680576