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: [-1, -9, -17, -25, -33, -41]
The following transformation applies to the sequence for the numerators: -5
This creates the following sequence: [7, 2, -3, -8, -13, -18]
Take a good look at how to rewrite the fractions in the series to recognize the pattern.
For example, 17/3 can be rewritten as -17/-3