a 12 − z 4 a 10 − 6 z 2 a 10 − 6 a 10 + 2 z 6 a 8 + 11 z 4 a 8 + 18 z 2 a 8 + 10 a 8 − z 8 a 6 − 6 z 6 a 6 − 13 z 4 a 6 − 15 z 2 a 6 − 8 a 6 + z 6 a 4 + 5 z 4 a 4 + 8 z 2 a 4 + 4 a 4 {\displaystyle a^{12}-z^{4}a^{10}-6z^{2}a^{10}-6a^{10}+2z^{6}a^{8}+11z^{4}a^{8}+18z^{2}a^{8}+10a^{8}-z^{8}a^{6}-6z^{6}a^{6}-13z^{4}a^{6}-15z^{2}a^{6}-8a^{6}+z^{6}a^{4}+5z^{4}a^{4}+8z^{2}a^{4}+4a^{4}}
