Data commit

Task/Anti-primes/Haskell/anti-primes.hs

@@ -0,0 +1,28 @@
+import Data.List (find, group)
+import Data.Maybe (fromJust)
+
+firstPrimeFactor :: Int -> Int
+firstPrimeFactor n = head $ filter ((0 ==) . mod n) [2 .. n]
+
+allPrimeFactors :: Int -> [Int]
+allPrimeFactors 1 = []
+allPrimeFactors n =
+  let first = firstPrimeFactor n
+  in first : allPrimeFactors (n `div` first)
+
+factorCount :: Int -> Int
+factorCount 1 = 1
+factorCount n = product ((succ . length) <$> group (allPrimeFactors n))
+
+divisorCount :: Int -> (Int, Int)
+divisorCount = (,) <*> factorCount
+
+hcnNext :: (Int, Int) -> (Int, Int)
+hcnNext (num, factors) =
+  fromJust $ find ((> factors) . snd) (divisorCount <$> [num ..])
+
+hcnSequence :: [Int]
+hcnSequence = fst <$> iterate hcnNext (1, 1)
+
+main :: IO ()
+main = print $ take 20 hcnSequence