0 = (-120*n^4-1240*n^3-4440*n^2-6440*n-3120+(132*n^4+1520*n^3+6320*n^2+11300*n+
7368)*N+(18*n^4+318*n^3+2044*n^2+5660*n+5712)*N^2+(-33*n^4-578*n^3-3761*n^2-\
10760*n-11400)*N^3+(3*n^4+61*n^3+458*n^2+1500*n+1800)*N^4)*x_n