Find an A.P. in which the sum of any number of terms is always three times the squared number of these terms.

Explanation

To find an Arithmetic Progression (A.P.) in which the sum of any number of terms is always three times the squared number of these terms, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**:
We need to find an A.P. such that the sum of the first \( n \) terms, denoted as \( S_n \), is equal to \( 3n^2 \).

2. **Formula for the Sum of the First n Terms**:
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