Poj Solution 1351

http://poj.org/problem?id=1351

/* @author:zeropinzuo */
import java.io.*;
import java.util.*;

public class Main{
 static Scanner cin;
 static long[] f,g;
    
 public static void main(String args[]){
  cin = new Scanner(System.in);
  f = new long[17];
  g = new long[17];
        
  g[1]=4;
  g[2]=14;
  for(int i=3;i< 17;i++)
    g[i]=3*g[i-1]+2*g[i-2];
        
  for(int i=2;i< 17;i++)
    f[i] = (1<< (2*i))-(1<< i)-g[i]+2;
            
  while(run()==true)
            ;
 }
    
 static boolean run(){
   int n = cin.nextInt();
   if(n==-1)
    return false;
   if(n==16){
     System.out.println(16+": 3553389280");
     return true;
    }
            
   System.out.println(n+": "+f[n]);
   return true;
    
  }
}