Data:9 30/HOMFLYPT Polynomial

$-z^6+2 a^2 z^4+z^4 a^{-2} -4 z^4-a^4 z^2+5 a^2 z^2+2 z^2 a^{-2} -7 z^2-a^4+4 a^2+2 a^{-2} -4$