In this sequence there are actually two sequences. 1 sequence for the numerators and one sequence for the denominators. The following transformation applies to the sequence for the denominators : +10
This creates the following sequence: [3, 13, 23, 33, 43]
The following transformation applies to the sequence for the numerators: +8
This creates the following sequence: [15, 23, 31, 39, 47]
Take a good look at how to rewrite the fractions in the series to recognize the pattern.
For example, 1/5 can be rewritten as 3/15