Expansion of (1-q)^k/Product_{j=1..k} (1-q^j) for k=7.

Terms

a(0) =1a(1) =-6a(2) =16a(3) =-25a(4) =26a(5) =-21a(6) =18a(7) =-21a(8) =27a(9) =-30a(10) =28a(11) =-26a(12) =30a(13) =-41a(14) =55a(15) =-65a(16) =66a(17) =-61a(18) =59a(19) =-66a(20) =79a(21) =-89a(22) =90a(23) =-85a(24) =84a(25) =-95a(26) =114a(27) =-127a(28) =126a(29) =-119