Claim:Σi = n(n+1)/2

Claim (see proof):

For all [math]n \href{/cs2800/wiki/index.php/%E2%88%88}{∈} \href{/cs2800/wiki/index.php/%E2%84%95}{ℕ} [/math], [math]\sum_{i=0}^n i = \frac{n(n+1)}{2} [/math]