Data commit

Task/Pernicious-numbers/F-Sharp/pernicious-numbers.fs

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+open System
+
+//Taken from https://gist.github.com/rmunn/bc49d32a586cdfa5bcab1c3e7b45d7ac
+let bitcount (n : int) =
+    let count2 = n - ((n >>> 1) &&& 0x55555555)
+    let count4 = (count2 &&& 0x33333333) + ((count2 >>> 2) &&& 0x33333333)
+    let count8 = (count4 + (count4 >>> 4)) &&& 0x0f0f0f0f
+    (count8 * 0x01010101) >>> 24
+
+//Modified from other examples to actually state the 1 is not prime
+let isPrime n =
+    if n < 2 then
+        false
+    else
+        let sqrtn n = int <| sqrt (float n)
+        seq { 2 .. sqrtn n } |> Seq.exists(fun i -> n % i = 0) |> not
+
+[<EntryPoint>]
+let main _ =
+    [1 .. 100] |> Seq.filter (bitcount >> isPrime) |> Seq.take 25 |> Seq.toList |> printfn "%A"
+    [888888877 .. 888888888] |> Seq.filter (bitcount >> isPrime) |> Seq.toList |> printfn "%A"
+    0 // return an integer exit code