Expansion of e.g.f. cos(x)/cosh(tan(x)), even powers only.

A009110

Expansion of e.g.f. cos(x)/cosh(tan(x)), even powers only.

Terms

    a(0) =1a(1) =-2a(2) =4a(3) =32a(4) =400a(5) =-3680a(6) =-719168a(7) =-45313024a(8) =-1201882880a(9) =190738937344

External references