a(n) = [x^(n*(n+1)/2)] Product_{k=1..n} (x^(k*(k+1)/2) + 1/x^(k*(k+1)/2)).

Terms

a(0) =1a(1) =1a(2) =0a(3) =0a(4) =0a(5) =2a(6) =0a(7) =3a(8) =3a(9) =5a(10) =0a(11) =14a(12) =23a(13) =39a(14) =0a(15) =101a(16) =161a(17) =315a(18) =0a(19) =971a(20) =1595a(21) =2872a(22) =0a(23) =9697a(24) =17431a(25) =31736a(26) =0a(27) =103608a(28) =190242a(29) =356883