− a 12 + 4 z 2 a 10 + 2 a 10 − 4 z 4 a 8 − 5 z 2 a 8 − 3 a 8 + z 6 a 6 + z 4 a 6 + 4 z 2 a 6 + 2 a 6 − 2 z 4 a 4 + z 2 a 4 + a 4 + 2 z 2 a 2 {\displaystyle -a^{12}+4z^{2}a^{10}+2a^{10}-4z^{4}a^{8}-5z^{2}a^{8}-3a^{8}+z^{6}a^{6}+z^{4}a^{6}+4z^{2}a^{6}+2a^{6}-2z^{4}a^{4}+z^{2}a^{4}+a^{4}+2z^{2}a^{2}}
