254809389793domain: NAppears in sequencescos(sec(x)*arcsinh(x))=1-1/2!*x^2-7/4!*x^4-145/6!*x^6-2063/8!*x^8...at n=8A012826E.g.f.: exp(sech(x)*arcsin(x))=1+x+1/2!*x^2-1/3!*x^3-7/4!*x^4+5/5!*x^5...at n=16A012878