An arithmetic sequence is a sequence of numbers such that the difference d between each consecutive term is a constant, the arithmetic sequence has the following explicit formula:
an = a1 + (n - 1)d
Where a1 is the first term and d is the common difference.
The common difference can be calculated by taking the difference between consecutive terms, like this:
d = 58 - 28 = 30
The first term a1, for this sequence is 28, then we can rewrite the explicit formula like this:
an = 28 + 30(n - 1)