View Code of Problem 3834

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cctype>
#include<vector>
#include<cmath>
using namespace std;
int main(void){
	int n;
	int arr[35];
	arr[0]=0;
	arr[1]=2;
	arr[2]=5;
	for(int i=3;i<35;i++){
		arr[i]=arr[i-1]*3-1;
	}
	while(cin>>n){
		cout<<arr[n]<<endl;
	}
}