C :

#include<stdio.h>
int main(){
int n,i;
  int sum=1;
  scanf("%d",&n);
  for(i=1;i<n;i++){
    sum=2*(sum+1);
  }
  printf("%d\n",sum);
  return 0;
}

C++ :

#include <stdio.h>
int main() {
	int i, n, tot;
	tot = 1;
	scanf("%d", &n);
	for (i = n;i > 1;i--) {
		tot = (tot + 1) * 2;
	}
	printf("%d\n", tot);
	return 0;
}

Pascal :

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

Java :

import java.util.*;
public class Main {
    public static void main(String args[]) {
        Scanner cin=new Scanner(System.in);
        int n=cin.nextInt();
        int[] a=new int[100];
        a[0]=1;
        for(int i=1;i<n;i++)
            a[i]=2*(a[i-1]+1);
        System.out.println(a[n-1]);
    }
}

Python :

def peachs(n):
    if n == 1:
        ps = 1
    else :
        ps = ((peachs(n-1))+1)*2
    return ps
    
t = int(raw_input())
print peachs(t)