initial commit

37.fs

@@ -0,0 +1,26 @@
+module _37
+
+let truncations i =
+    let s = string i
+    let len = s.Length
+    seq {
+        for n in 0..(len - 1) do
+            yield s.Substring(0, len - n) 
+            if (n > 0) then
+                yield s.Substring(len - n)
+    } |> Seq.distinct |> Seq.toList |> List.map (int)
+
+let truncatablePrimes =
+    let oddOr2 i = i % 2 = 1 || i = 2
+        
+    let pa = 
+        common.primeArray 1000000
+        |> Array.filter (common.numDigits >> (Array.forall oddOr2))
+        
+    let isPrime n = Array.exists (fun p -> p = n) pa
+    pa
+    |> Array.filter ((<) 10)
+    |> Array.map truncations
+    |> Array.filter (List.forall isPrime)
+    |> Array.map (Seq.nth 0)
+    |> Array.sum