The given sequence is an arithmetic sequence beacuse there is a common difference between consecutive terms. We can determine this by subtracting the consecutive terms as shown below
Common difference, d = 8 - 3 = 13 - 8 = 18 - 13 = 5
The explicit equation for an arithmetic sequence is written as
an = a1 + d(n - 1)
The first term, a1 = 3
n is the number of terms
d is the common difference aand it is 3
By substituting these values into the equation, the explicit formula for this sequence is
an = 3 + 5(n - 1)