Find the sum to n terms of the series :`5^2+6^2+7^2+.......+20^2`

Explanation

To find the sum of the series \(5^2 + 6^2 + 7^2 + \ldots + 20^2\), we can follow these steps:

### Step 1: Identify the series
The series we need to sum is from \(5^2\) to \(20^2\). We can express this as:
\[ S = 5^2 + 6^2 + 7^2 + \ldots + 20^2 \]

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