Definition:Square Number/Definition 3

Definition
Square numbers are defined as:
 * $\ds S_n = \sum_{i \mathop = 1}^n \paren {2 i - 1} = 1 + 3 + 5 + \cdots + \paren {2 n - 1}$

for $n = 1, 2, 3, \ldots$

Also see

 * Equivalence of Definitions of Square Number