arctanh(arctan(tanh(x)))=x-2/3!*x^3+24/5!*x^5-944/7!*x^7+77952/9!*x^9...

A012228

arctanh(arctan(tanh(x)))=x-2/3!*x^3+24/5!*x^5-944/7!*x^7+77952/9!*x^9...

Terms

    a(0) =1a(1) =-2a(2) =24a(3) =-944a(4) =77952a(5) =-10623744a(6) =2145104896a(7) =-602082207744

External references