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 : +8
This creates the following sequence: [9, 17, 25, 33, 41, 49]
The following transformation applies to the sequence for the numerators: +4
This creates the following sequence: [11, 15, 19, 23, 27, 31]