q 13 − 2 q 12 + 3 q 11 − 5 q 10 + 6 q 9 − 7 q 8 + 6 q 7 − 5 q 6 + 4 q 5 − 2 q 4 + 2 q 3 {\displaystyle q^{13}-2q^{12}+3q^{11}-5q^{10}+6q^{9}-7q^{8}+6q^{7}-5q^{6}+4q^{5}-2q^{4}+2q^{3}}
