To find the relationship you:
1. The relation can be the difference between every term in the sequence:
In the first sequence you have between every term a diferencen of:
Where n is the term
Youn can notice that the relationship is the way you get that term and is equal to the previous term plus an odd number (3,5,7,9), as the sequences do not have a constant difference the sequence is a non-regular succession. But as the set of differences (1,3,5,7,9) Follows a regular succesion of (2n-1) you have quadratic sequences that have the next formula:
1. First sequence:
2. Second sequence: