− z 6 + a 2 z 4 + z 4 a 2 − 4 z 4 + 2 a 2 z 2 + 2 z 2 a 2 − 5 z 2 + a 2 + 1 a 2 − 1 {\displaystyle -z^{6}+a^{2}z^{4}+{\frac {z^{4}}{a^{2}}}-4z^{4}+2a^{2}z^{2}+{\frac {2z^{2}}{a^{2}}}-5z^{2}+a^{2}+{\frac {1}{a^{2}}}-1}
