#include <stdio.h>

int main(void) {
	int n=4;
	int a,b,c;
	b=2;
	c=1;
	for(int i=3;i<=n;i++){
		a=-6*b-9*c;
		c=b;
		b=a;
	}
	printf("数列a%dの値は%d\n",n,a);
	// your code goes here
	return 0;
}