E.g.f. log(sech(x) + tan(x)).

Terms

a(0) =0a(1) =1a(2) =-2a(3) =7a(4) =-24a(5) =165a(6) =-1232a(7) =10827a(8) =-111104a(9) =1316585a(10) =-17449472a(11) =257028847a(12) =-4164086784a(13) =73616009805