q 18 t 7 + 2 q 16 t 6 + q 14 t 6 + 3 q 14 t 5 + 2 q 12 t 5 + 3 q 12 t 4 + 3 q 10 t 4 + 4 q 10 t 3 + 3 q 8 t 3 + 3 q 8 t 2 + 4 q 6 t 2 + 2 q 6 t + 3 q 4 t + 2 q 4 + q − 2 t − 2 + q 2 t − 1 + 4 q 2 {\displaystyle q^{18}t^{7}+2q^{16}t^{6}+q^{14}t^{6}+3q^{14}t^{5}+2q^{12}t^{5}+3q^{12}t^{4}+3q^{10}t^{4}+4q^{10}t^{3}+3q^{8}t^{3}+3q^{8}t^{2}+4q^{6}t^{2}+2q^{6}t+3q^{4}t+2q^{4}+q^{-2}t^{-2}+q^{2}t^{-1}+4q^{2}}