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Some Useful Summation Formulae

$tex:\displaystyle \sum_{i=1}^{n}{i} = \frac{n(n+1)}{2}$

$tex:\displaystyle \sum_{i=1}^{n}{i^2} = \frac{n(n+1)(2n+1)}{6}$

$tex:\displaystyle \sum_{i=1}^{n}{i^3} = \frac{n^2(n+1)^2}{4}$

keywords: summations, formula, squared, cubed, sum