import java.util.Scanner;
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc=new Scanner(System.in);
int k=sc.nextInt();
System.out.println((int)(Math.pow(2,k)-k-1)*2);
}
}
原文：http://www.cnblogs.com/watchfree/p/5769082.html