Sum of Sequence of Squares

Theorem

 * $\displaystyle \forall n \in \N: \sum_{i \mathop = 1}^n i^2 = \frac {n \left({n + 1}\right) \left({2 n + 1}\right)} 6$

Historical Note
This theorem was proved by during the course of his proofs of the volumes of various solids of revolution in his On Conoids and Spheroids.

It was also documented by in his work Āryabhaṭīya of 499 CE.