Question: 1. Give an example of a sequence that is not an integer sequence.
2. Find a sequence different from an = 2n that satisfies the recurrence an = 2an-1.
3. Find the recurrence that defines the sequence 1,3,6,10,15,... .
4. Find a description for the sequence 2,3,5,7,11,13,... . Can you find a closed form or a recurrence that defines this sequence?