1 #include <stdio.h> 2 #include <stdlib.h> 3 int main() 4 { 5 int n,sum,i; 6 while(scanf("%d",&n)!=EOF&&n!=0) 7 { 8 sum=1; 9 for(i=1; i<n; i++) 10 { 11 sum=sum*2+2; 12 } 13 printf("%d\n",sum); 14 } 15 return 0; 16 }