View Code of Problem 3692

# include <stdio.h>
# include <stdlib.h>
# include <math.h>
# include <string.h>
 
int main()
{
    int n;
    long long dp[51];
    dp[0] = 0,dp[1] = 3,dp[2] = 6,dp[3] = 6;
    for(int i = 4;i <= 50;i++){
        dp[i] = dp[i - 1] + dp[i - 2] * 2;
    }
    while(scanf("%d",&n) != EOF){
 
        printf("%lld\n",dp[n]);
    }
	return 0;
}