Find sum to n terms of the series `1+(2+3)+(4+5+6)+"...."`.

Explanation

To find the sum to n terms of the series \( S = 1 + (2 + 3) + (4 + 5 + 6) + \ldots \), we will break down the problem step by step.

### Step 1: Identify the pattern in the series
The series can be rewritten as:
- The first term is \( 1 \) (which is \( 1 \) term),
- The second term is \( 2 + 3 \) (which is \( 2 \) terms),
- The third term is \( 4 + 5 + 6 \) (which is \( 3 \) terms),
- The fourth term is \( 7 + 8 + 9 + 10 \) (which is \( 4 \) terms),
...