Mathematics for IGCSE & O level - Sequences (Section 2 - No. 6)
Which of the following sequences is a quadratic sequence?
5, 10, 15, 20, ...
1, 3, 5, 7, ...
1, 4, 7, 10, ...
2, 4, 8, 16, ...
Explication
A quadratic sequence has a constant second difference.