#include <stdio.h>
int count = 0;
int rec(int n) {
    count++;  
 
    if (n == 1){
          return 2;
    }
    else if (n == 2){
          return 3;
    }
    else return 2 * rec(n - 1) + rec(n - 2);
}
 
int main(void) {
    int n;
    printf("nの値を入力してください: ");
    scanf("%d", &n);
 
    int ans = rec(n);
    printf("数列aの第%d項の値は%d\n", n, ans);
    printf("このときrecの呼び出し回数は%d回です。\n", count);
 
    return 0;
}
 

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