tanh(arctan(x)*arctan(x))=2/2!*x^2-16/4!*x^4+128/6!*x^6+9984/8!*x^8...

A012463

tanh(arctan(x)*arctan(x))=2/2!*x^2-16/4!*x^4+128/6!*x^6+9984/8!*x^8...

Terms

    a(0) =0a(1) =2a(2) =-16a(3) =128a(4) =9984a(5) =-1686528a(6) =211630080a(7) =-21438504960a(8) =-115777536000

External references