c#
public class Program
{
    public static int[] GenerateDivisors(int n)
    {
        if (n <= 0)
        {
            return null;
        }
        List<int> divisors = new List<int>();
        for (int i = 1; i <= Math.Sqrt(n); i++)
        {
            if (n % i == 0)
            {
                divisors.Add(i);
                if (i != n / i)
                {
                    divisors.Add(n / i);
                }
            }
        }
        divisors.Sort();
        divisors.Remove(n);
        return divisors.ToArray();
    }

    public static int GetSumOfDivisors(int[] x)
    {
        int total = 0;
        for (int i = 0; i < x.Length; i++)
        {
            total += x[i];
        }
        
        return total;
    }
    private static void GetNextNumber(int x)
    {
        var values = GenerateDivisors(x);
        var sum = GetSumOfDivisors(values);
        
        while (true)
        {
            Console.WriteLine(x);
            if (x == 0)
            {
                return;
            }
            GetNextNumber(sum);
        }
    }

    public static void Main(string[] args)
    {
        GetNextNumber(18);
    }
}

c#
public class Program
{
    public static int[] GenerateDivisors(int n)
    {
        if (n <= 0)
        {
            return null;
        }
        List<int> divisors = new List<int>();
        for (int i = 1; i <= Math.Sqrt(n); i++)
        {
            if (n % i == 0)
            {
                divisors.Add(i);
                if (i != n / i)
                {
                    divisors.Add(n / i);
                }
            }
        }
        divisors.Sort();
        divisors.Remove(n);
        return divisors.ToArray();
    }

    public static int GetSumOfDivisors(int[] x)
    {
        int total = 0;
        for (int i = 0; i < x.Length; i++)
        {
            total += x[i];
        }
        
        return total;
    }
    private static void GetNextNumber(int x)
    {
        var values = GenerateDivisors(x);
        var sum = GetSumOfDivisors(values);
        
        while (true)
        {
            Console.WriteLine(x);
            if (x == 0)
            {
                return;
            }
            GetNextNumber(sum);
        }
    }

    public static void Main(string[] args)
    {
        GetNextNumber(18);
    }
}

C#
C#
public static void Main(string[] args)
    {
        Console.WriteLine(IsPalindrome(121));
    }
    private static bool IsPalindrome(int x)
    {
        var input = (x + "").ToCharArray();
        return input.Equals(Reverse(input));
    }
    
    private static char[] Reverse(char[] input)
    {
        char[] output = new char[input.Length];
        int index = 0;
        for (int i = input.Length - 1; i >= 0; i--)
        {
            output[index] = input[i];
            index++;
        }
        return output;
    }

C#
C#
public static void Main(string[] args)
    {
        Console.WriteLine(IsPalindrome(121));
    }
    private static bool IsPalindrome(int x)
    {
        var input = (x + "").ToCharArray();
        return input.Equals(Reverse(input));
    }
    
    private static char[] Reverse(char[] input)
    {
        char[] output = new char[input.Length];
        int index = 0;
        for (int i = input.Length - 1; i >= 0; i--)
        {
            output[index] = input[i];
            index++;
        }
        return output;
    }