arctanh(arctan(sin(x))) = x - 1/3!*x^3 + 9/5!*x^5 - 393/7!*x^7 + 25329/9!*x^9 - ...

A012191

arctanh(arctan(sin(x))) = x - 1/3!*x^3 + 9/5!*x^5 - 393/7!*x^7 + 25329/9!*x^9 - ...

Terms

    a(0) =1a(1) =-1a(2) =9a(3) =-393a(4) =25329a(5) =-2720433a(6) =438412857a(7) =-97949820153

External references