Expansion of e.g.f.: tanh(tan(x)/cos(x)).

A009818

Expansion of e.g.f.: tanh(tan(x)/cos(x)).

Terms

    a(0) =1a(1) =3a(2) =-23a(3) =-2149a(4) =-73967a(5) =4773747a(6) =1496400505a(7) =166245767819

External references