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