C :

#include <stdio.h>

long int howmany(int n)
{
 int i;
 long int s=1;
 for (i = 1; i<n; i++) s=2*(s+1);
 return s;
}
int main(void)
{
 int whatday;
 scanf("%d",&whatday);
 printf("%ld",howmany(whatday));
 return 0;
}

C++ :

#include<iostream>
using namespace std;
int main(){
	int x=1,i,n,sum=0;
    cin>>n;
    for (i=0;i<n-1;i++){
        x=x*2+2;

    }
    cout<<x<<endl;
    return 0;
}

Pascal :

var n,a,i:longint; 
begin 
  readln(n); 
  a:=1; 
  for i:=1 to n-1 do 
    a:=(a+1)*2; 
  writeln(a); 
end.