FUNCTION :  qseries[theta3] - the theta function  theta (q)
                                                       3
CALLING SEQUENCE :  theta3(q,T)       
    
PARAMETERS :   q   - variable 
               T   - positive integer 
   
SYNOPSIS :   
                                                        T 
 theta3(q,t) returns the q-series expansion to order O(q ) of 

                                  oo
                                 -----     2
                                  \       n
              theta (q)   =        )     q
                   3              /
                                 -----
                                n = - oo

EXAMPLES :   
   
-------------------------------------------------------------------------
> theta3(q,50);                             


            64      49      36      25      16      9      4
         2 q   + 2 q   + 2 q   + 2 q   + 2 q   + 2 q  + 2 q  + 2 q + 1

----------------------------------------------------------------------------   
SEE  ALSO :   jacprod, tripleprod, theta, theta2, theta4