Find the sum of the series `1+4+7+10+.......` to 40 terms.

Explanation

To find the sum of the series \(1 + 4 + 7 + 10 + \ldots\) up to 40 terms, we can recognize that this is an arithmetic progression (AP).

### Step-by-Step Solution:

1. **Identify the first term (a) and the common difference (d)**:
- The first term \(a = 1\).
- The common difference \(d = 4 - 1 = 3\).

...