E.g.f. exp(sec(x)-sech(x)) (even powers only).

A013503

E.g.f. exp(sec(x)-sech(x)) (even powers only).

Terms

    a(0) =1a(1) =2a(2) =12a(3) =242a(4) =8512a(5) =438722a(6) =34406592a(7) =3496736882a(8) =471749623552

External references