Problem2856--递归/递推-精卫填海

2856: 递归/递推-精卫填海

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 49  Solved: 43
[Status] [Submit] [Creator:]

Description

精卫捡来一大堆石子,他每次把1/2石子扔到海里,之后再多扔2个,重复n次后,只剩下了2颗石头,问最开始有多少颗石头

Sample Input Copy 

5

Sample Output Copy 

188

Source/Category

 
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