#include <stdio.h>
//練習問題F
 
 
int main(void) {
	int n = 3, an = -1;
	for(int i=1; i<=n; i++)
		an=3*an+5;
    printf("数列anについて, n=%dのときの値は%d\n", n
, an
); 	return 0;
}
 
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