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

Terms

a(0) =1a(1) =0a(2) =1a(3) =4a(4) =8a(5) =12a(6) =17a(7) =24a(8) =36a(9) =56a(10) =88a(11) =136a(12) =205a(13) =300a(14) =428a(15) =600a(16) =828a(17) =1132a(18) =1540a(19) =2084a(20) =2813a(21) =3788a(22) =5080a(23) =6788a(24) =9032a(25) =11952a(26) =15736a(27) =20612a(28) =26852a(29) =34812