#include <stdio.h>
//練習問題E
 
int tri(int n){
	if(n==0||n==1){
		return 0;
	}
	else if(n==2){
		return 1;
	}
	else{
		return tri(n-1)+tri(n-2)+tri(n-3);
	}
}	
 
int main(void) {
	int n = 7;
    printf("数列Tnについて, n=%dのときの値は%d\n", n
, tri
(n
)); 	return 0;
}
 
				I2luY2x1ZGUgPHN0ZGlvLmg+Ci8v57e057+S5ZWP6aGMRQoKaW50IHRyaShpbnQgbil7CglpZihuPT0wfHxuPT0xKXsKCQlyZXR1cm4gMDsKCX0KCWVsc2UgaWYobj09Mil7CgkJcmV0dXJuIDE7Cgl9CgllbHNlewoJCXJldHVybiB0cmkobi0xKSt0cmkobi0yKSt0cmkobi0zKTsKCX0KfQkKCmludCBtYWluKHZvaWQpIHsKCWludCBuID0gNzsKICAgIHByaW50Zigi5pWw5YiXVG7jgavjgaTjgYTjgaYsIG49JWTjga7jgajjgY3jga7lgKTjga8lZFxuIiwgbiwgdHJpKG4pKTsKCXJldHVybiAwOwp9Cg==