− 1 q 7 / 2 − 1 q 11 / 2 + 1 q 15 / 2 − 1 q 21 / 2 {\displaystyle -{\frac {1}{q^{7/2}}}-{\frac {1}{q^{11/2}}}+{\frac {1}{q^{15/2}}}-{\frac {1}{q^{21/2}}}}
