亲密数

#include <stdio.h>
int main()
{
int a, i, b, n;
printf("There are following friendly - numbers pair smaller than 3000:\n");

for (a = 1; a < 3000; a++)
{

for (b = 0, i = 1; i <= a / 2; i++ )
{
if(! (a % i))
{
b += i;
}
}

for (n = 0, i = 1; i <= b/2; i++)
{
if(! (b % i))
{
n += i;
}
}

if(n == a && a < b)
{
printf("%4d..%4d\n", a, b);
}

}
return 0;
}