294715261521domain: NAppears in sequencessec(arcsin(arcsinh(x)))=1+1/2!*x^2+5/4!*x^4+109/6!*x^6+3177/8!*x^8...at n=8A012121Expansion of e.g.f. exp(arctanh(arcsinh(x))).at n=16A012262