Display the groups of friend numbers (which have the same sum of divisors)

FriendNumbers.scala

object FriendNumbers extends App {
  def sumOfDivisors(n: Int) =
    (for {
      i <- 1 to Math.sqrt(n).toInt
      if n % i == 0
    } yield i + n / i).sum

  val friendGroups = (1 to 10000).groupBy(sumOfDivisors).filter(_._2.size > 1).toList.sortBy(_._1)
  println(friendGroups)
}