题目

英语翻译
Out of N soldiers,standing in one line,it is required to choose several to send them scouting.
In order to do that,the following operation is performed several times:if the line consists of more than three soldiers,then all soldiers,standing on even positions,or all soldiers,standing on odd positions,are taken away.The above is done until three or less soldiers are left in the line.They are sent scouting.Find,how many different groups of three scouts may be created this way.
Note:Groups with less than three number of soldiers are not taken into consideration.

提问时间：2021-04-01

答案

有N个士兵排成一行,现在需要选出几个人去侦察.
为了完成这个可执行如下操作：如果有多于三个士兵,那么所有在奇数位置（或所有在偶数位置）的将被剔除.重复执行,直到不多于三个士兵.他们就是要被派遣去侦察的人.
求出通过这方法,可以产生有多少组三个士兵的结果.

注意：产生少于三个士兵的不在考虑范围