for i in [-4..6] do 
   print "i = ", i;
   for a in [1,2,4,8] do
      for b in [1,2,4,8] do
         e := PowerSeries(f,21)
               -  q*Evaluate(e,q^a)^i*Evaluate(e,q^b)^(6-i) + O(q^10);
print "e = ", e;
         if e eq 0 + O(q^10) then
            print i, a, b;
         end if;
      end for;
   end for;
end for;
           
