#include <stdio.h>
 
int main(void) {
    // 漸化式の初期値 (a1 = 1, a2 = 2)
    int a1 = 1;
    int a2 = 2;
    int an;
    int n = 4; // 求めたい項数（初期値は4）
 
    printf("a_1 = %d\n", a1);
    printf("a_2 = %d\n", a2);
 
    // 第3項から第n項まで計算するループ
    for (int i = 3; i <= n; i++) {
        // 漸化式: an = -6 * a_{n-1} - 9 * a_{n-2}
        an = -6 * a2 - 9 * a1;
 
        // 【修正のポイント】古い値を順にズラしていく
        a1 = a2; // 先に a1 に古い a2 の値を移す
        a2 = an; // その後、a2 に新しい計算結果 an を入れる
 
        printf("a_%d = %d\n", i, an);
    }
 
    return 0;
}
 

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