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

A009011

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

Terms

    a(0) =1a(1) =1a(2) =-3a(3) =-3a(4) =665a(5) =-25031a(6) =607893a(7) =13065717a(8) =-3684215119a(9) =322746228337

External references