I have to factorise $2(x^2 + x^3 + x^4 + x^5 + x^6 + x^7)$. It seems that there a very simple expression to which simply this polynomial.

The only thing I found so far is $2 x^2 (1 + x + x^2 + x^3 + x^4 + x^5)$. Can you explain to me in details how to factorise this even more? If so, is there a general rule for such similar polynomial?