− z 2 a 14 + z 4 a 12 − 2 z 2 a 12 − 3 a 12 + 3 z 4 a 10 + 4 z 2 a 10 + 2 a 10 + z 6 a 8 + 7 z 4 a 8 + 8 z 2 a 8 + 2 a 8 + z 6 a 6 + 5 z 4 a 6 + 4 z 2 a 6 {\displaystyle -z^{2}a^{14}+z^{4}a^{12}-2z^{2}a^{12}-3a^{12}+3z^{4}a^{10}+4z^{2}a^{10}+2a^{10}+z^{6}a^{8}+7z^{4}a^{8}+8z^{2}a^{8}+2a^{8}+z^{6}a^{6}+5z^{4}a^{6}+4z^{2}a^{6}}