These are the first 5 terms of a quadratic sequence:

Question

1 3 7 13 21

1st difference: 2 4 6 8
2nd difference: 2 2 2

1n^2: 1 4 9 16 25

adjustment: ? ? ? ? ?

Thank you very much.

Answer 1

well, check the differences:

1-1=0
4-3=1
9-7=2
16-13=3
25-21=4

So, how does that relate to n?