static void Main()
{
var x = DivisorSums.Factorial(4);
var y = DivisorSums.pow(10, 6);
Console.WriteLine(DivisorSums.D(x, y));
}
public static List <int> ListDivisor(int x)
{
List <int> L = new List <int>(); //Create an Empty list of int
for (int i = 1; i <= x; i++)
{
if (DivisorSums.isDivide(i, x))
{
L.Add(i);
}
}
return(L);
}
//=============================================================
//Calculating D(m,n)
public static int D(int m, int n)
{
int S = 0;
foreach (var d in DivisorSums.ListDivisor(m))
{
for (int k = 1; k <= n; k++)
{
S = S + DivisorSums.sigma(k * d);
}
}
return(S);
}
public static int sigma(int n)
{
// Returns the number of divisors of n.
int s = 0;
for (int i = 1; i <= n; i++)
{
if (DivisorSums.isDivide(i, n))
{
s = s + 1;
}
}
return(s);
}
