arctanh(tan(tan(x)))=x+6/3!*x^3+176/5!*x^5+12240/7!*x^7...

A012152

arctanh(tan(tan(x)))=x+6/3!*x^3+176/5!*x^5+12240/7!*x^7...

Terms

    a(0) =1a(1) =6a(2) =176a(3) =12240a(4) =1561088a(5) =318007808a(6) =94807748608

External references