initial commit

23.fs

@@ -0,0 +1,28 @@
+module _23
+
+let abundantUpperLimit = 28123
+
+let abundantNumbers =
+    let dSums = 
+        common.divisors abundantUpperLimit
+        |> Array.mapi (fun i divisors -> (i,  List.fold (+) 0 divisors))
+    dSums |> Array.choose ( fun (i, dSum) -> 
+        match dSum with
+        | abundant when dSum > i -> Some(i)
+        | _ -> None
+        )
+
+let sumNotAbundant = 
+    let a = abundantNumbers
+    // add all abubundant numbers together
+    
+    let sums = common.crossMap (+) a a |> Seq.distinct |> Seq.toArray
+
+    let sna = 
+        sums
+        |> Set.ofSeq
+        |> (-) (Set.ofList [1..abundantUpperLimit])
+        |> Set.toSeq
+        //|> Array.rev
+
+    sna |> Seq.fold (+) 0