n(n+1)(n+2)(n+3)(n+4)
n(n+1)(n+2)(n+3)(n+4)=(n(n+1)(n+2)(n+3))(n+4)=(n(n+1)(n+2)(n+3))(n)+(n(n+1)(n+2)(n+3))(4)=n^5+6n^4+11n^3+6n^2+4n^4+24n^3+44n^2+24n=n^5+10n^4+35n^3+50n^2+24n