Simple Collatz sequence implementation

Collatz.scala

//scala3 version in https://scastie.scala-lang.org/oswaldo/D18phCIFTzuH14BHLxKTNA/6
object Collatz extends App {
  val stop = BigInt(1)

  def sequence(n: BigInt): Stream[BigInt] = Stream(n) #::: {
    n match {
      case `stop` =>
        println(s"$n, stopping")
        Stream.empty[BigInt]
      case step => sequence(if (n % 2 == 0) {
        println(s"$n is even\n  => $n / 2")
        n / 2
      } else {
        println(s"$n is odd\n  => 3 * $n + 1")
        3 * n + 1
      }
      )
    }
  }

  val n = BigInt(42)
  //val n = BigDecimal("1e100").toBigInt

  val s = sequence(n)

  println(s"Collatz for $n:\n\n")

  println("\nsequence: " + s.mkString(", "))
  println("size: " + s.size)
}