−z2a10−a10z−2−a10 + 3z4a8 + 8z2a8 + 4a8z−2 + 8a8−2z6a6−9z4a6−17z2a6−5a6z−2−15a6 + 3z4a4 + 9z2a4 + 2a4z−2 + 8a4