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

A009089

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

Terms

    a(0) =1a(1) =0a(2) =8a(3) =-56a(4) =3968a(5) =-133248a(6) =13993088a(7) =-1139191808a(8) =178943504384

External references