View Code of Problem 73

#include <stdio.h>

int sum(int n)
{
    int i,sum = 1;
    for(i = 1;i < n;i++)
    {
        sum = 2 * (sum + 1);
    }
    return sum;

}

int main(void)
{
    int n;
    while(scanf("%d",&n) != EOF)
    {
        printf("%d\n",sum(n));
    }
    return 0;
}