#include <stdio.h>

int get_sum_divisor(int n)
{
    int x, sum;

    sum = 0;
    for (x = 1; x <= n; x++)
    {
        sum += x;
    }

    return sum;
}

int main(void)
{
    int k;

    for (k = 5; k <= 15; k += 5)
    {
        printf("%3d の約数の合計 = %d\n", k, get_sum_divisor(k));
    }

    return 0;
}