To find Sn, we need to find the sum of the first n terms of the geometric sequence.

The common ratio (r) can be found by dividing any term by its previous term. In this case, we can divide 3 by 1 to get r = 3/1 = 3.

The formula for Sn of a geometric sequence is given by: Sn = a * (r^n - 1) / (r - 1)

where a is the first term, r is the common ratio, and n is the number of terms.

In this case, a = 1, r = 3, and we need to find Sn.

Let’s calculate Sn for n = 5: Sn = 1 * (3^5 - 1) / (3 - 1) = 1 * (243 - 1) / 2 = 1 * 242 / 2 = 121

Therefore, Sn = 121.