View Code of Problem 3834

#include<stdio.h>
#include<math.h>
int main()
{
	int n;
	while(scanf("%d",&n)!=EOF)
	{
		int sum=0;
		int num=0;
		for(int i=0;i<=n;i=i+2)
		{
			num=pow(2,n-i);
//			printf("%d\n",num); 
			sum+=num;
		}
		printf("%d\n",sum);
	}
}