# Complexity! (7)

Algebra Level 4

Evaluate the following sum in terms of $$n$$,

$\displaystyle \sum_{k=1}^n (k+1)\left(k + \dfrac{1}{\omega}\right)\left(k + \dfrac{1}{\omega^2}\right)$

Notations: $$\omega$$ and $$\omega^2$$ are non-real cube roots of unity.