#include <stdio.h>

int c = 0;

int rec(int n) {

    c++;
    
    if (n == 1) return 2;
    if (n == 2) return 3;
    
    return 2 * rec(n - 1) + rec(n - 2);
}

int main(void) {
    int n = 5; 

    c = 0; 
    
    int result = rec(n);

    printf("数列a%dの値は%d\n", n, result);
    
    printf("回数は%d\n", c);
    
    return 0;
}