A012773 exp(cosh(x)*arctanh(x))=1+x+1/2!*x^2+6/3!*x^3+21/4!*x^4+100/5!*x^5...

1, 1, 1, 6, 21, 100, 645, 4256, 34153, 302352, 2966505, 32245664, 380114493, 4879093440, 67244074989, 996485811712, 15717842398417, 264232448010496, 4694489063253585, 88283645811756544, 1744673430747688805