−z2a10−a10z−2−2a10 + z6a8 + 6z4a8 + 11z2a8 + 4a8z−2 + 10a8−z8a6−7z6a6−17z4a6−21z2a6−5a6z−2−16a6 + z6a4 + 6z4a4 + 11z2a4 + 2a4z−2 + 8a4