View Code of Problem 3834

#include <iostream>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std; 
int main(){ 
  	int n;
 	while(cin>>n){
	  	if(n==1){
	  		cout<<2<<endl;
	  		continue;
		}
		long long sum=0;
		for(int i=0;i<=n;i+=2){
			
			int m=pow(2,n-i);
			if(i==0)//如果0块绿色 
				sum+=m;
			else {
				sum=sum+(n-i+1)*m;
			}
			
		} 
  		 cout<<sum<<endl;
  	}
	return 0;
}