E.g.f.: Sum_{n>=0} arctanh(n*x)^n/n!.

A221079

E.g.f.: Sum_{n>=0} arctanh(n*x)^n/n!.

Terms

    a(0) =1a(1) =1a(2) =4a(3) =29a(4) =384a(5) =8009a(6) =222272a(7) =8007621a(8) =368537600a(9) =20666061201

External references