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

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =3a(7) =2a(8) =3a(9) =5a(10) =5a(11) =8a(12) =11a(13) =11a(14) =17a(15) =19a(16) =22a(17) =33a(18) =38a(19) =50a(20) =69a(21) =82a(22) =103a(23) =133a(24) =165a(25) =201a(26) =249a(27) =319a(28) =389a(29) =492