gistfile1.scala

  @tailrec
  private def eulerTotient(f: List[Tuple2[LargeInt, Int]], retval: Rational): LargeInt = {
  
    f match {
      case Nil => retval.dividend
      case ::(h, t) =>
        eulerTotient(
          t,
          retval * Rational(h._1 - LargeInt.One, h._1)
        )
    }
    
  }