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

Terms

a(0) =1a(1) =21a(2) =273a(3) =2716a(4) =22659a(5) =165984a(6) =1098615a(7) =6695559a(8) =38085117a(9) =204218630a(10) =1040291595a(11) =5064987207a(12) =23686610269a(13) =106828575357a(14) =466231753944