Life On VM

def findPrimeFactors(number : Int) : List[Int] = {
  val first_prime_or_none = (2 until Math.sqrt(number)).inclusive.find { i => number % i == 0 }
  if (first_prime_or_none != None) {
    return first_prime_or_none.get :: findPrimeFactors(number / first_prime_or_none.get)
  }
  number :: Nil
}

(2 until 100).inclusive.foreach {
    number => println(  "Prime factors of " + number + " is " +
                        findPrimeFactors(number).removeDuplicates.mkString("[", ", ", "]") )
}

static void Main(string[] args)
{
    for (int number = 2; number <= 33; number++)
        Console.WriteLine("Prime factors of {0} is [{1}]",
                number, String.Join(", ", FindPrimeFactors(number)
                    .ToList().ConvertAll<string>(x => x.ToString())
                    .ToArray())
                );
}

static HashSet<int> FindPrimeFactors(int number)
{
    var firstPrimeOrNone = Enumerable.Range(2, (int)Math.Ceiling(Math.Sqrt(number)))
        .ToList().Find(x => number % x == 0);

    if (firstPrimeOrNone != 0)
    {
        var ret = FindPrimeFactors(number / firstPrimeOrNone);
        ret.Add(firstPrimeOrNone);
        return ret;
    }

    return new HashSet<int>(new int[] { number }); ;
}

static void Main(string[] args)
{
    for (int number = 2; number <= 33; number++)
        Console.WriteLine("Prime factors of {0} is [{1}]",
                number, String.Join(", ", FindPrimeFactors(number)
                    .Distinct().Select(x => x.ToString()).ToArray())
                );
}

static IEnumerable<int> FindPrimeFactors(int number)
{
    while (true)
    {
        var firstPrimeOrNone = Enumerable.Range(2, (int)Math.Ceiling(Math.Sqrt(number)))
            .ToList().Find(x => number % x == 0);

        if (firstPrimeOrNone != 0)
        {
            yield return firstPrimeOrNone; number /= firstPrimeOrNone;
        }
        else
        {
            yield return number; break;
        }
    }
}