Expansion of Product_{k>=1} (1 + k!*x^k).

Terms

a(0) =1a(1) =1a(2) =2a(3) =8a(4) =30a(5) =156a(6) =900a(7) =6192a(8) =47904a(9) =422928a(10) =4138848a(11) =44864640a(12) =531227520a(13) =6836927040a(14) =94891046400