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