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

Terms

a(0) =1a(1) =1a(2) =2a(3) =13a(4) =48a(5) =381a(6) =3120a(7) =26923a(8) =255696a(9) =3158137a(10) =40008240a(11) =519979791a(12) =7942304040a(13) =122856625477