Expansion of Product_{k >= 1} (1 - x^k)^4.

Terms

a(0) =1a(1) =-4a(2) =2a(3) =8a(4) =-5a(5) =-4a(6) =-10a(7) =8a(8) =9a(9) =0a(10) =14a(11) =-16a(12) =-10a(13) =-4a(14) =0a(15) =-8a(16) =14a(17) =20a(18) =2a(19) =0a(20) =-11a(21) =20a(22) =-32a(23) =-16a(24) =0a(25) =-4a(26) =14a(27) =8a(28) =-9a(29) =20