Expansion of e.g.f. exp(-x^4/4)/(1-x).

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =18a(5) =90a(6) =540a(7) =3780a(8) =31500a(9) =283500a(10) =2835000a(11) =31185000a(12) =372972600a(13) =4848643800a(14) =67881013200