C :

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<ctype.h>
#include<math.h>
int a[10005],s[10005];
//每次都计算 a数组*k 
void ans(int k){ //123
	int i;
	//每一位都乘以k 
	for(i=0;i<10000;i++){
		a[i] = a[i]*k;
	}
	for(i=0;i<10000;i++){
		a[i+1] = a[i+1] + a[i]/10;
		a[i] = a[i]%10;
	}
}
void add(){
	int i;
	for(i=0;i<10000;i++){
		s[i] = s[i]+a[i];
		s[i+1] = s[i+1] + s[i]/10;
		s[i] = s[i]%10; 
	}
}
int main(){
	int n,i,j;
	scanf("%d",&n);

	for(i=1;i<=n;i++){
		memset(a,0,sizeof(a)); 
		a[0] = 1; 
		for(j=1;j<=i;j++){
			ans(2);
		}
		add();
	}

	int p=1000;
	for(i=p;i>=0;i--){
		if(s[i]!=0){
			p = i;
			break;
		}
	}
	for(i=p;i>=0;i--){
		printf("%d",s[i]);
	}
	return 0;
}

C++ :

#include <bits/stdc++.h>
using namespace std;

int main(){
	int a[100][100] = {0};
	int r[100] = {0};
	int i,j,n;
	cin>>n;
	a[0][0] = 1;
	int k = 1;
	for(i = 1;i <= n;i++){
		for(j = 0;j < k;j++){
			a[i][j] = a[i - 1][j] * 2;
		}
		
		for(j = 0;j < k;j++){
			if(a[i][j] >= 10){
				a[i][j + 1] = a[i][j + 1] + a[i][j] / 10;
				a[i][j] = a[i][j] % 10; 
			}
		}
		
		if(a[i][k] > 0){
			k++;
		}
	}
	
	//求和
	for(i = 1;i <= n;i++){
		for(j = 0;j < k;j++){
			r[j] = r[j] + a[i][j];
			
			if(r[j] >= 10){
				r[j + 1] += r[j] / 10;
				r[j] = r[j] % 10;
			}
		}
		
		if(r[k] > 0){
			k++;
		}
	}
	
	int p = 0;
	for(i = k - 1;i >= 0;i--){
		if(r[i] != 0){
			p = i;
			break;
		}
	} 

	for(i = p;i >= 0;i--){
		cout<<r[i];
	} 
}

Python :

print(2**int(input())*2-2)