every :: [a] -> Int -> [a]
every [] _ = []
every (x:xs) n = allepaar (x:xs) 1 n
  where allepaar :: [a] -> Int -> Int -> [a]
        allepaar [] _ _ = []
        allepaar (x:xs) z n = if mod z n == 0 then x: allepaar xs (z+1) n else allepaar xs (z+1) n