988579109

Appears in sequences

• arctanh(arctanh(x)*cos(x)) = x+1/3!*x^3+13/5!*x^5+677/7!*x^7+54937/9!*x^9...at n=6A012746
• Expansion of e.g.f. log(sec(x)+arctanh(x)).at n=13A013200