21267520

Appears in sequences

• sin(tan(arcsinh(x)))=x-4/5!*x^5-136/7!*x^7+272/9!*x^9-222016/11!*x^11...at n=6A012160
• Expansion of e.g.f.: exp(tanh(arcsin(x)))=1+x+1/2!*x^2-3/4!*x^4-4/5!*x^5+21/6!*x^6...at n=13A012255