-log(cosh(x)*cos(x))=-4/4!*x^4-544/8!*x^8-707584/12!*x^12...

A012770

-log(cosh(x)*cos(x))=-4/4!*x^4-544/8!*x^8-707584/12!*x^12...

Terms

    a(0) =4a(1) =544a(2) =707584a(3) =3807514624

External references