Expansion of e.g.f. 1 / (1 - x + x^2/2 - x^3/3).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =10a(5) =50a(6) =230a(7) =1260a(8) =9240a(9) =76440a(10) =651000a(11) =6006000a(12) =62739600a(13) =719518800a(14) =8736327600a(15) =112588476000