Expansion of Product_{m>=1} (1-m*q^m)^21.

Terms

a(0) =1a(1) =-21a(2) =168a(3) =-511a(4) =-756a(5) =8946a(6) =-13265a(7) =-41604a(8) =100023a(9) =168819a(10) =-192675a(11) =-1687035a(12) =551446a(13) =9388890a(14) =39015a(15) =-23757153a(16) =-51335655a(17) =33287667a(18) =289673223a(19) =168014469a(20) =-413315910a(21) =-2158209675a(22) =-1508351355a(23) =6477445065