− z 4 a 12 − 4 z 2 a 12 − 3 a 12 + 2 z 6 a 10 + 10 z 4 a 10 + 14 z 2 a 10 + 6 a 10 − z 8 a 8 − 6 z 6 a 8 − 13 z 4 a 8 − 14 z 2 a 8 − 6 a 8 + 2 z 6 a 6 + 10 z 4 a 6 + 13 z 2 a 6 + 4 a 6 {\displaystyle -z^{4}a^{12}-4z^{2}a^{12}-3a^{12}+2z^{6}a^{10}+10z^{4}a^{10}+14z^{2}a^{10}+6a^{10}-z^{8}a^{8}-6z^{6}a^{8}-13z^{4}a^{8}-14z^{2}a^{8}-6a^{8}+2z^{6}a^{6}+10z^{4}a^{6}+13z^{2}a^{6}+4a^{6}}