−za7 + 2z3a5 + 3za5 + 2a5z−1 + a5z−3−z5a3−4z3a3−9za3−7a3z−1−3a3z−3 + z5a + 7z3a + 11za + 8az−1 + 3az−3−z3a−1−4za−1−3a−1z−1−a−1z−3