Data commit

Task/Prime-decomposition/Elixir/prime-decomposition.elixir

@@ -0,0 +1,15 @@
+defmodule Prime do
+  def decomposition(n), do: decomposition(n, 2, [])
+
+  defp decomposition(n, k, acc) when n < k*k, do: Enum.reverse(acc, [n])
+  defp decomposition(n, k, acc) when rem(n, k) == 0, do: decomposition(div(n, k), k, [k | acc])
+  defp decomposition(n, k, acc), do: decomposition(n, k+1, acc)
+end
+
+prime = Stream.iterate(2, &(&1+1)) |>
+        Stream.filter(fn n-> length(Prime.decomposition(n)) == 1 end) |>
+        Enum.take(17)
+mersenne = Enum.map(prime, fn n -> {n, round(:math.pow(2,n)) - 1} end)
+Enum.each(mersenne, fn {n,m} ->
+  :io.format "~3s :~20w = ~s~n", ["M#{n}", m, Prime.decomposition(m) |> Enum.join(" x ")]
+end)