#include <stdio.h>
int tri(int n) {
if (n <= 1) return 0;
if (n == 2) return 1;
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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