E.g.f.: Product_{k>=1} (1 + sin(x^k)).

Terms

a(0) =1a(1) =1a(2) =2a(3) =11a(4) =48a(5) =341a(6) =2640a(7) =23561a(8) =228816a(9) =2674153a(10) =32749200a(11) =440019469a(12) =6504919080a(13) =102077649805