Expansion of e.g.f. 1 / (1 - x)^sech(x).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =35a(6) =285a(7) =2044a(8) =13804a(9) =108093a(10) =1083405a(11) =12281896a(12) =143452386a(13) =1763156031a(14) =23845410407a(15) =353626471808