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