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

Terms

a(0) =1a(1) =21a(2) =252a(3) =2275a(4) =17052a(5) =111594a(6) =657419a(7) =3557256a(8) =17931459a(9) =85093393a(10) =383211885a(11) =1648114587a(12) =6803773998a(13) =27073141326a(14) =104199172863a(15) =389047640905