1
Input: 2 → [?] → 6, what is the rule? =
2
Input: 9 → [?] → 45, what is the rule? =
3
Input: 7 → [?] → 4, what is the rule? =
4
Input: 7 → [?] → 9, what is the rule? =
5
Input: 5 → [?] → 10, what is the rule? =
7
Input: 2 → [?] → 4, what is the rule? =