Problem 73

73.hs

@@ -0,0 +1,10 @@
+import Data.Ratio
+
+numOfFrac bound = sum $ map (\d -> let nLower = ceiling (d % 3)
+                                       nUpper = floor   (d % 2) 
+                                   in length [n | n <- [nLower..nUpper], 
+                                                  let ratio = (n % d), ratio > (1 % 3), ratio < (1 % 2), 
+                                                  denominator ratio == d])
+                        [2..bound]
+
+main = print $ numOfFrac 12000