a z 7 + z 7 a + a 2 z 6 + z 6 a 2 + 2 z 6 + a 3 z 5 − 4 a z 5 − 4 z 5 a + z 5 a 3 + a 4 z 4 − 2 a 2 z 4 − 2 z 4 a 2 + z 4 a 4 − 6 z 4 − 2 a 3 z 3 + 8 a z 3 + 8 z 3 a − 2 z 3 a 3 − 3 a 4 z 2 + a 2 z 2 + z 2 a 2 − 3 z 2 a 4 + 8 z 2 − 4 a z − 4 z a + a 4 + 1 a 4 − 1 {\displaystyle az^{7}+{\frac {z^{7}}{a}}+a^{2}z^{6}+{\frac {z^{6}}{a^{2}}}+2z^{6}+a^{3}z^{5}-4az^{5}-{\frac {4z^{5}}{a}}+{\frac {z^{5}}{a^{3}}}+a^{4}z^{4}-2a^{2}z^{4}-{\frac {2z^{4}}{a^{2}}}+{\frac {z^{4}}{a^{4}}}-6z^{4}-2a^{3}z^{3}+8az^{3}+{\frac {8z^{3}}{a}}-{\frac {2z^{3}}{a^{3}}}-3a^{4}z^{2}+a^{2}z^{2}+{\frac {z^{2}}{a^{2}}}-{\frac {3z^{2}}{a^{4}}}+8z^{2}-4az-{\frac {4z}{a}}+a^{4}+{\frac {1}{a^{4}}}-1}
