1
Input: 3 → [?] → 13, what is the rule? =
3
Input: 6 → [?] → 15, what is the rule? =
4
Input: 6 → [?] → 20, what is the rule? =
5
Input: 9 → [?] → 8, what is the rule? =
6
Input: 10 → [?] → 23, what is the rule? =
7
Input: 10 → [?] → 50, what is the rule? =