collatz :: Int -> [Int]
collatz n | n == 1 = [n]
          | even n = n : (collatz $ n `quot` 2)
          | otherwise = n : (collatz $ 3*n + 1)
collatz :: Int -> [Int]
collatz n | n == 1 = [n]
          | even n = n : (collatz $ n `quot` 2)
          | otherwise = n : (collatz $ 3*n + 1)
collatz n | n == 1 = [n]
          | even n = n : (collatz $ n `quot` 2)
          | otherwise = n : (collatz $ 3*n + 1)