Find the least value of `n` for which the sum `1+3+3^2+ ton` terms is greater than 7000.

Explanation

To find the least value of \( n \) for which the sum \( S_n = 1 + 3 + 3^2 + \ldots + 3^{n-1} \) is greater than 7000, we can use the formula for the sum of a geometric series.

### Step 1: Identify the formula for the sum of a geometric series
The sum of the first \( n \) terms of a geometric series can be calculated using the formula:
\[ S_n = a \frac{(r^n - 1)}{(r - 1)} \]
where \( a \) is the first term, \( r \) is the common ratio, and \( n \) is the number of terms.
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