Expansion of e.g.f. 1 / (exp(-x^2/2) - x).

Terms

a(0) =1a(1) =1a(2) =3a(3) =12a(4) =63a(5) =420a(6) =3345a(7) =31080a(8) =330225a(9) =3946320a(10) =52401195a(11) =765404640a(12) =12196214415a(13) =210533843520