G.f.: x * Product_{k>=1} (1 + a(k)*x^k)^k.

Terms

a(0) =1a(1) =1a(2) =2a(3) =8a(4) =39a(5) =240a(6) =1723a(7) =14165a(8) =130459a(9) =1331530a(10) =14894260a(11) =181259007a(12) =2383643794a(13) =33692516860a(14) =509433237073