(q;q)a1+a2+β‹―+an(q;q)a1⁒(q;q)a2⁒⋯⁒(q;q)an=Β coeff. of ⁒x10⁒x20⁒⋯⁒xn0⁒ in ⁒∏1≀j<k≀n(xjxk;q)aj⁒(q⁒xkxj;q)ak.