read `RecSum.txt`;
rec:=simplify(RecSum(6,4,10,1,(3*n^3-4)+(n^2+1)*N - 4*n*N^3,binomial(n,k),n,k,N)/N^n):
lprint(0 = (add(coeff(rec,N,i)*N^i,i=0..degree(rec,N)))*x_n);

quit;