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

A009107

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

Terms

    a(0) =1a(1) =0a(2) =-8a(3) =56a(4) =512a(5) =-54912a(6) =2590336a(7) =-69311488a(8) =-3936710656a(9) =914002857984

External references