-((1 - x + 6*x*z + 4*x*z^2 + 7*x^2*z^2 - x^3*z^2 + 4*x*z^3 + 6*x^2*z^3 + 
   4*x*z^4 + x^2*z^4 + 4*x^3*z^4 + x^4*z^4 + 6*x*z^5 - 10*x^2*z^5 + 
   2*x^3*z^5 + 6*x^4*z^5 - x*z^6 + 5*x^2*z^6 - 14*x^3*z^6 + 10*x^4*z^6 - 
   10*x^2*z^7 - 12*x^3*z^7 + 4*x^4*z^7 + x^2*z^8 - 36*x^3*z^8 + 6*x^4*z^8 - 
   x^5*z^8 + 6*x^2*z^9 - 38*x^3*z^9 + 8*x^4*z^9 - 6*x^5*z^9 + 7*x^2*z^10 - 
   36*x^3*z^10 + 19*x^4*z^10 - 20*x^5*z^10 - 12*x^3*z^11 + 36*x^4*z^11 - 
   36*x^5*z^11 - 14*x^3*z^12 + 55*x^4*z^12 - 41*x^5*z^12 + 2*x^3*z^13 + 
   36*x^4*z^13 - 16*x^5*z^13 - 4*x^6*z^13 + 4*x^3*z^14 + 19*x^4*z^14 + 
   17*x^5*z^14 - 10*x^6*z^14 + 8*x^4*z^15 + 28*x^5*z^15 - 6*x^6*z^15 - 
   x^3*z^16 + 6*x^4*z^16 + 17*x^5*z^16 + 8*x^6*z^16 + 4*x^4*z^17 - 
   16*x^5*z^17 + 24*x^6*z^17 + 10*x^4*z^18 - 41*x^5*z^18 + 31*x^6*z^18 + 
   6*x^4*z^19 - 36*x^5*z^19 + 24*x^6*z^19 + x^4*z^20 - 20*x^5*z^20 + 
   8*x^6*z^20 + x^7*z^20 - 6*x^5*z^21 - 6*x^6*z^21 + 2*x^7*z^21 - x^5*z^22 - 
   10*x^6*z^22 + x^7*z^22 - 4*x^6*z^23)/((-1 + x)^2*(-1 + x*z^2)*(-1 + x*z^4)*
   (-1 + x*z^2 + 2*x*z^3 + x*z^4)*(-1 + x*z^6)^2))
