G.f.: Product_{k>=1, j>=1} (1+x^(j*k^2)).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =5a(7) =7a(8) =9a(9) =13a(10) =16a(11) =20a(12) =27a(13) =34a(14) =42a(15) =53a(16) =67a(17) =82a(18) =102a(19) =125a(20) =153a(21) =188a(22) =227a(23) =274a(24) =332a(25) =401a(26) =478a(27) =574a(28) =686a(29) =815