The sum of the first \(n\) terms of the series\\ \(1^{2} + 2 \cdot 2^{2} + 3^{2} + 2 \cdot 4^{2} + 5^{2} + 2 \cdot 6^{2} + \ldots\ldots\ldots\) is \(\frac{n(n + 1)^{2}}{2}\), when \(n\) is even. when \(n\) is odd, the sum is