E.g.f. arctanh(tan(x)*tan(x)) (even powers only).

A012393

E.g.f. arctanh(tan(x)*tan(x)) (even powers only).

Terms

    a(0) =0a(1) =2a(2) =16a(3) =512a(4) =34816a(5) =4063232a(6) =724566016a(7) =183240753152

External references