Expansion of Sum_{k>=0} k! * x^(k*(k+1)/2) / Product_{j=1..k} (1 - x^j)^j.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =3a(5) =7a(6) =13a(7) =19a(8) =31a(9) =57a(10) =99a(11) =145a(12) =253a(13) =391a(14) =661a(15) =1071a(16) =1647a(17) =2617a(18) =4189a(19) =6439a(20) =10183a(21) =15999a(22) =24195a(23) =37537a(24) =57553a(25) =87925a(26) =132841a(27) =202899a(28) =306147a(29) =458827