q 4 − 4 q 3 + 6 q 2 − 7 q + 9 − 7 q + 6 q 2 − 4 q 3 + 1 q 4 {\displaystyle q^{4}-4q^{3}+6q^{2}-7q+9-{\frac {7}{q}}+{\frac {6}{q^{2}}}-{\frac {4}{q^{3}}}+{\frac {1}{q^{4}}}}
