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

Terms

a(0) =1a(1) =1a(2) =4a(3) =6a(4) =17a(5) =25a(6) =59a(7) =89a(8) =187a(9) =284a(10) =545a(11) =828a(12) =1505a(13) =2270a(14) =3930a(15) =5904a(16) =9861a(17) =14695a(18) =23827a(19) =35248a(20) =55775a(21) =81882a(22) =126874a(23) =184870a(24) =281467a(25) =407065a(26) =610193a(27) =876282a(28) =1295892a(29) =1848144