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

A009086

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

Terms

    a(0) =1a(1) =-1a(2) =1a(3) =47a(4) =449a(5) =-18209a(6) =-1441087a(7) =-41192817a(8) =2660018305a(9) =460752070079

External references