property("longs are evenly-distributed") =
    forAll { (seed: Seed, b: Base) =>
      val base = b.value

      def countZeros(s0: Seed, i: Int, seen0: Int): Int =
        if (i <= 0) seen0 else {
          val (x, s1) = s0.long
          val n = (x & 0x7fffffff).toInt % base
          val seen = if (n == 0) seen0 + 1 else seen0
          countZeros(s1, i - 1, seen)
        }

      val count = 10000
      val mean = count.toDouble / base
      val stdDev = Math.sqrt(mean * ((base.toDouble - 1) / base))
      val delta = 5 * stdDev // 1 in 1.7M false positives
      val zeros = countZeros(seed, count, 0)
      (mean - delta) <= zeros && zeros <= (mean + delta)
    }