G.f.: Sum_{k>=0} x^(k^2) * Product_{j=1..k} 1/(1 - x^j)^3.

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =11a(5) =18a(6) =30a(7) =47a(8) =75a(9) =115a(10) =177a(11) =264a(12) =394a(13) =573a(14) =831a(15) =1184a(16) =1679a(17) =2349a(18) =3273a(19) =4511a(20) =6192a(21) =8428a(22) =11422a(23) =15372a(24) =20606a(25) =27453a(26) =36435a(27) =48103a(28) =63270a(29) =82833