1
Input: 5 → [?] → 11, what is the rule? =
2
Input: 9 → [?] → 21, what is the rule? =
4
Input: 9 → [?] → 8, what is the rule? =
6
Input: 5 → [?] → 2, what is the rule? =
7
Input: 4 → [?] → 14, what is the rule? =
8
Input: 4 → [?] → 16, what is the rule? =