#include <stdio.h>
//練習問題E
int tri(int n){
if (n==0){
return 0;}
else if (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;}
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