q 21 / 2 − 2 q 19 / 2 + 3 q 17 / 2 − 6 q 15 / 2 + 7 q 13 / 2 − 9 q 11 / 2 + 9 q 9 / 2 − 8 q 7 / 2 + 6 q 5 / 2 − 4 q 3 / 2 + 2 q − 1 q {\displaystyle q^{21/2}-2q^{19/2}+3q^{17/2}-6q^{15/2}+7q^{13/2}-9q^{11/2}+9q^{9/2}-8q^{7/2}+6q^{5/2}-4q^{3/2}+2{\sqrt {q}}-{\frac {1}{\sqrt {q}}}}
