Data:K13n2931/HOMFLYPT Polynomial

[math]\displaystyle{ z^2 a^8-2 z^4 a^6-z^2 a^6+2 a^6+z^6 a^4-4 z^2 a^4-4 a^4+z^6 a^2+2 z^4 a^2+3 z^2 a^2+2 a^2-z^4-z^2+1 }[/math]