diff --git a/src/3n+1/Main.hs b/src/3n+1/Main.hs
index 37f7d9f..e42bbb5 100755
--- a/src/3n+1/Main.hs
+++ b/src/3n+1/Main.hs
@@ -7,7 +7,7 @@ import           Control.Monad ()
 import           Debug.Trace   (trace)
 
 f' :: Integer -> Integer
-f' n = f'' 0 n
+f' n = f'' 1 n
   where
     f'' :: Integer -> Integer -> Integer
     f'' i n'
@@ -19,14 +19,13 @@ f' n = f'' 0 n
             t'' = trace "\n#######################################################\n"
 
 f :: Integer -> Integer
-f n = s 0 n
+f n = s 1 n
   where
     s :: Integer -> Integer -> Integer
     s i n
       | n == 1 = i
-      | even n = s i' (n `div` 2)
-      | odd  n = s i' (3*n + 1)
-      where i' = succ i
+      | even n = s (succ i) (n `div` 2)
+      | odd  n = s (succ i) (3*n + 1)
 
 main :: IO ()
 main = print $ map f [2^361..]