arctan(arctanh(x)+arctan(x))=2*x-16/3!*x^3+816/5!*x^5-100224/7!*x^7...

A013178

arctan(arctanh(x)+arctan(x))=2*x-16/3!*x^3+816/5!*x^5-100224/7!*x^7...

Terms

    a(0) =2a(1) =-16a(2) =816a(3) =-100224a(4) =23046912a(5) =-8501907456

External references