Data commit

Task/Mian-Chowla-sequence/Haskell/mian-chowla-sequence.hs

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+import Data.Set (Set, fromList, insert, member)
+
+------------------- MIAN-CHOWLA SEQUENCE -----------------
+mianChowlas :: Int -> [Int]
+mianChowlas =
+  reverse . snd . (iterate nextMC (fromList [2], [1]) !!) . subtract 1
+
+nextMC :: (Set Int, [Int]) -> (Set Int, [Int])
+nextMC (sumSet, mcs@(n:_)) =
+  (foldr insert sumSet ((2 * m) : fmap (m +) mcs), m : mcs)
+  where
+    valid x = not $ any (flip member sumSet . (x +)) mcs
+    m = until valid succ n
+
+--------------------------- TEST -------------------------
+main :: IO ()
+main =
+  (putStrLn . unlines)
+    [ "First 30 terms of the Mian-Chowla series:"
+    , show (mianChowlas 30)
+    , []
+    , "Terms 91 to 100 of the Mian-Chowla series:"
+    , show $ drop 90 (mianChowlas 100)
+    ]