杭电oj_2047——阿牛的EOF牛肉串（java实现）

package hduoj;

import java.util.Scanner;

public class hdoj_2047 {
    /**
     * 得出递归式：f(n) = 2*[f(n-1)+f(n-2)]
     */
    public static void main(String[] args) {
        long[] data = new long[41];
        data[1] = 3;
        data[2] = 8;
        for(int  i = 3;i<41;++i){
            data[i] = 2*(data[i - 1]+data[i - 2]);
        }
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            System.out.println(data[sc.nextInt()]);
        }
    }
}