Explanation:
The first differences are 7,9,11,13,15,17 and the second differences are 2.
This means that the first term of the sequence is n^2.
Subtracting n^2 from the sequence gives 6,10,14,18,22,26, which has nth term of 4n + 2.
So putting these together gives a nth term of the quadratic sequence of n^2 + 4n + 2.
Hope it helped and tell me if I went wrong :)