q − 2 + 4 q − 5 q 2 + 6 q 3 − 5 q 4 + 4 q 5 − 3 q 6 + 1 q 7 {\displaystyle q-2+{\frac {4}{q}}-{\frac {5}{q^{2}}}+{\frac {6}{q^{3}}}-{\frac {5}{q^{4}}}+{\frac {4}{q^{5}}}-{\frac {3}{q^{6}}}+{\frac {1}{q^{7}}}}