#include <stdio.h>
 
// 関数のプロトタイプ宣言
int sum_sequence(int n);
 
int main() {
    int n, result;
 
    // n = 4 の場合
    n = 4;
    result = sum_sequence(n);
    printf("n=%d の場合の合計は %d\n", n, result);
 
    // n = 5 の場合
    n = 5;
    result = sum_sequence(n);
    printf("n=%d の場合の合計は %d\n", n, result);
 
    return 0;
}
 
// 関数の定義
int sum_sequence(int n) {
    int total = 0;
    int current_term = 0;
    int i;
 
    for (i = 1; i <= n; ++i) {
        current_term = current_term * 10 + 4;
        total += current_term;
    }
 
    return total;
}
 

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