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 : +7
This creates the following sequence: [-3, 4, 11, 18, 25, 32, 39]
The following transformation applies to the sequence for the numerators: -5
This creates the following sequence: [9, 4, -1, -6, -11, -16, -21]
Take a good look at how to rewrite the fractions in the series to recognize the pattern.
For example, -1/3 can be rewritten as -3/9