Week 6: if you have read this and you have no questions, please close this issue.

[BertLisser]

Clear concise report (++) with beauties of Haskell functions like

-- Exercise 3: Composites sieve.
composites :: [Integer]
composites = map fst (filter (not . snd) (sieve' [2..]))

-- characterize numbers by prime property
sieve' :: [Integer] -> [(Integer,Bool)]
sieve' ns = let ps = (sieve [2..])
            in map (\ n -> (n, (inlist n ps))) ns
            where inlist n (p:ps) | p < n = inlist n ps
                                  | p == n = True
                                  | otherwise = False

The test results are very readable. One remark:
There are more carmichael numbers than {(6k+1)(12k+1)(18k+1)}
(see solutions Lab6)