Data:10 91/HOMFLYPT Polynomial

$z^8-a^2 z^6-z^6 a^{-2} +6 z^6-4 a^2 z^4-4 z^4 a^{-2} +13 z^4-5 a^2 z^2-5 z^2 a^{-2} +12 z^2-2 a^2-2 a^{-2} +5$