a(n) = [x^(2n)y^n] Product_{i>=1} 1/((1-x^(2i-1)y^i)(1-x^(2i-1)y^(i-1))(1-x^(2i)y^i)^2).

Terms

a(0) =1a(1) =3a(2) =10a(3) =27a(4) =69a(5) =161a(6) =361a(7) =767a(8) =1578a(9) =3134a(10) =6064a(11) =11432a(12) =21105a(13) =38175a(14) =67863a(15) =118658a(16) =204455a(17) =347439a(18) =583063a(19) =966952a(20) =1586231a(21) =2575474a(22) =4141832a(23) =6600731a(24) =10430455a(25) =16349788a(26) =25434178a(27) =39280676a(28) =60250276a(29) =91810915