Coefficient of y^0 in G(x,y)^3 where G(x,y) = Sum_{n=-oo..+oo} (1-x^n)^n * x^n * y^n.

Terms

a(0) =1a(1) =-6a(2) =3a(3) =6a(4) =12a(5) =-12a(6) =3a(7) =-30a(8) =18a(9) =-48a(10) =63a(11) =-30a(12) =51a(13) =-36a(14) =129a(15) =-168a(16) =147a(17) =-78a(18) =-42a(19) =-120a(20) =279a(21) =-372a(22) =195a(23) =-180a(24) =339a(25) =-294a(26) =351a(27) =-588a(28) =969a(29) =-444