− 1 q 9 / 2 − 1 q 13 / 2 + 1 q 21 / 2 − 1 q 23 / 2 {\displaystyle -{\frac {1}{q^{9/2}}}-{\frac {1}{q^{13/2}}}+{\frac {1}{q^{21/2}}}-{\frac {1}{q^{23/2}}}}
