#include <stdio.h>
//a{n} = -6a{n-1} -9a{n-2}, a{1}=1, a{2}=2(再帰あり版)
int c;
 
int rec(int n){
	if(n == 1) {
		c++;
		return 1;
	}
	else if(n == 2) {
		c++;
		return 2;
	}
	else {
		c++;
		printf("この時recが呼び出された回数は%c\n", c);
		return - 6 * rec(n-1) - 9 * rec(n-2);
	}
}
int main(void) {
    int n = 4;
    printf("数列a%dの値は%d\n", n, rec(n));
    printf("この時recが呼び出された回数は%c\n", c);
	return 0;
}
 
 

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