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

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =7a(6) =9a(7) =13a(8) =17a(9) =22a(10) =30a(11) =38a(12) =48a(13) =62a(14) =78a(15) =97a(16) =122a(17) =151a(18) =184a(19) =228a(20) =278a(21) =335a(22) =408a(23) =491a(24) =588a(25) =707a(26) =843a(27) =1000a(28) =1189a(29) =1407