Expansion of Product_{k>=1} (1-q^(2*k))/(1-q^k)^4.

Terms

a(0) =1a(1) =4a(2) =13a(3) =36a(4) =90a(5) =208a(6) =455a(7) =948a(8) =1901a(9) =3688a(10) =6955a(11) =12792a(12) =23019a(13) =40612a(14) =70395a(15) =120072a(16) =201822a(17) =334684a(18) =548158a(19) =887500a(20) =1421602a(21) =2254460a(22) =3541928a(23) =5515900a(24) =8519173a(25) =13055208a(26) =19859113a(27) =29998024a(28) =45012751a(29) =67116436