arctanh(arctanh(x)*arctan(x))=2/2!*x^2+448/6!*x^6+2380032/10!*x^10...

A012734

arctanh(arctanh(x)*arctan(x))=2/2!*x^2+448/6!*x^6+2380032/10!*x^10...

Terms

    a(0) =2a(1) =448a(2) =2380032a(3) =69695846400

External references