A012879 exp(sech(x)*arctan(x))=1+x+1/2!*x^2-4/3!*x^3-19/4!*x^4+20/5!*x^5...

1, 1, 1, -4, -19, 20, 565, 1024, -24743, -147568, 1450985, 19148736, -100090043, -2934842560, 5608180253, 551525234688, 703874231473, -127249126657792, -601015521145391, 35789287036394496, 309193460848468125