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

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =11a(5) =22a(6) =40a(7) =70a(8) =116a(9) =191a(10) =304a(11) =474a(12) =726a(13) =1094a(14) =1624a(15) =2384a(16) =3453a(17) =4950a(18) =7030a(19) =9890a(20) =13798a(21) =19108a(22) =26264a(23) =35858a(24) =48652a(25) =65615a(26) =87996a(27) =117396a(28) =155826a(29) =205854