a(n) = [x^n] Product_{k>=1} (1 + x^k)*(1 - x^(n*k))/((1 - x^k)*(1 + x^(n*k))).

Terms

a(0) =1a(1) =0a(2) =2a(3) =6a(4) =12a(5) =22a(6) =38a(7) =62a(8) =98a(9) =152a(10) =230a(11) =342a(12) =502a(13) =726a(14) =1038a(15) =1470a(16) =2060a(17) =2862a(18) =3946a(19) =5398a(20) =7334a(21) =9902a(22) =13286a(23) =17726a(24) =23526a(25) =31064a(26) =40822a(27) =53406a(28) =69566a(29) =90246