q 9 / 2 − 4 q 7 / 2 + 8 q 5 / 2 − 13 q 3 / 2 + 18 q − 21 q + 21 q 3 / 2 − 19 q 5 / 2 + 13 q 7 / 2 − 9 q 9 / 2 + 4 q 11 / 2 − 1 q 13 / 2 {\displaystyle q^{9/2}-4q^{7/2}+8q^{5/2}-13q^{3/2}+18{\sqrt {q}}-{\frac {21}{\sqrt {q}}}+{\frac {21}{q^{3/2}}}-{\frac {19}{q^{5/2}}}+{\frac {13}{q^{7/2}}}-{\frac {9}{q^{9/2}}}+{\frac {4}{q^{11/2}}}-{\frac {1}{q^{13/2}}}}
