− a 5 z 9 + a 7 z 7 − 7 a 5 z 7 + a 3 z 7 + 5 a 7 z 5 − 18 a 5 z 5 + 5 a 3 z 5 + 8 a 7 z 3 − 21 a 5 z 3 + 7 a 3 z 3 + 5 a 7 z − 9 a 5 z + 2 a 3 z + a 5 z − 1 − a 3 z − 1 {\displaystyle -a^{5}z^{9}+a^{7}z^{7}-7a^{5}z^{7}+a^{3}z^{7}+5a^{7}z^{5}-18a^{5}z^{5}+5a^{3}z^{5}+8a^{7}z^{3}-21a^{5}z^{3}+7a^{3}z^{3}+5a^{7}z-9a^{5}z+2a^{3}z+a^{5}z^{-1}-a^{3}z^{-1}}
