-661302639

Appears in sequences

• cos(tan(arctanh(x)))=1-1/2!*x^2-15/4!*x^4-561/6!*x^6-38623/8!*x^8...at n=6A012178
• Expansion of e.g.f.: exp(tanh(arctan(x)))=1+x+1/2!*x^2-3/3!*x^3-15/4!*x^4+41/5!*x^5...at n=12A012256