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 a z 5 + 2 z 5 a + 2 z 5 a 3 + a 4 z 4 − a 2 z 4 − z 4 a 2 + z 4 a 4 − 4 z 4 − 3 a 3 z 3 − 3 a z 3 − 3 z 3 a − 3 z 3 a 3 − 2 a 4 z 2 − 2 a 2 z 2 − 2 z 2 a 2 − 2 z 2 a 4 + a 3 z + z a 3 + a 4 + a 2 + 1 a 2 + 1 a 4 + 1 {\displaystyle az^{7}+{\frac {z^{7}}{a}}+2a^{2}z^{6}+{\frac {2z^{6}}{a^{2}}}+4z^{6}+2a^{3}z^{5}+2az^{5}+{\frac {2z^{5}}{a}}+{\frac {2z^{5}}{a^{3}}}+a^{4}z^{4}-a^{2}z^{4}-{\frac {z^{4}}{a^{2}}}+{\frac {z^{4}}{a^{4}}}-4z^{4}-3a^{3}z^{3}-3az^{3}-{\frac {3z^{3}}{a}}-{\frac {3z^{3}}{a^{3}}}-2a^{4}z^{2}-2a^{2}z^{2}-{\frac {2z^{2}}{a^{2}}}-{\frac {2z^{2}}{a^{4}}}+a^{3}z+{\frac {z}{a^{3}}}+a^{4}+a^{2}+{\frac {1}{a^{2}}}+{\frac {1}{a^{4}}}+1}
