 prim[1] =   x[1]
 prim[2] =   x[1]*x[2]
 prim[3] =   x[1]^2
 prim[4] =   x[1]*x[2]*x[3]
 prim[5] =   x[1]^3
 prim[6] =   x[1]*x[2]*x[3]*x[4]
 prim[7] =   x[1]^4
 prim[8] =   x[1]*x[2]*x[5]*x[3]*x[4]
 prim[9] =   x[1]^5
 prim[10] =   x[1]^6
