quadratric sequences

intending to familiarise students with the properties of a growing quadratic sequence
rather than finding a quadratic rule from a (given) procedure

the second resource was suggested by David Wells
intending to explore the differences - possibly by students looking at a few quadratic rules to discover generalities for themselves

you might choose to just use the second resource
hopefully students will appreciate the symmetry of some sequences

possibly exploring when a growing quadratic sequence has symmetry and when it has not