Expansion of e.g.f.: 1/cos(tan(x)) (even-indexed coefficients only).

A009010

Expansion of e.g.f.: 1/cos(tan(x)) (even-indexed coefficients only).

Terms

    a(0) =1a(1) =1a(2) =13a(3) =397a(4) =22265a(5) =1996569a(6) =262056837a(7) =47378857957

External references