Data update

Task/Arithmetic-numbers/Haskell/arithmetic-numbers.hs

@@ -0,0 +1,31 @@
+import Data.Numbers.Primes
+import Data.List
+
+import Text.Printf
+import Data.List.Split
+import Control.Monad
+
+isArithCompo :: Int -> (Bool, Bool)
+isArithCompo n = (mod sumFs numFs == 0, numFs > 2)
+  where
+    pks = map (\xs -> (head xs, length xs)) $ group $ primeFactors n
+    sumFs = product [div (pred $ p ^ succ k) (pred p) | (p,k) <- pks]
+    numFs = product $ map (succ . snd) pks
+
+task1 :: [Int]
+task1 = take 100 [i | i <- [1 ..], fst $ isArithCompo i]
+
+task23 :: [(Int, Int, Int)]
+task23 = map sub [10^3,10^4,10^5,10^6]
+  where
+    sub cnt = (cnt, fst $ ics !! pred cnt, length $ filter snd $ take cnt ics)
+    ics = [(i, c) | i <- [1 ..], let (a, c) = isArithCompo i, a]
+
+main :: IO ()
+main = do
+  forM_ (chunksOf 10 $ map (printf "%4d") task1) (\as -> sequence_ as >> putChar '\n')
+  putChar '\n'
+  forM_ task23 (\(i,a,c) -> do
+    printf "%dth arithmetic number is %d\n" i a
+    printf "Number of composite arithmetic numbers <= %d: %d\n\n" a c
+    )