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module Seq357 where

is357 :: Integer -> Bool
is357 a = (((mod a 3) == 0) && is357 (div a 3))
 || ((mod a 5) == 0) && is357 (div a 5)
 || ((mod a 7) == 0) && is357 (div a 7)
 || (a == 1)

seq357 :: [Integer] 
seq357 = [x | x <- [1,2..],is357 x]

--seq357n n :: Int -> [Integer]
seq357n n = take n seq357


divides :: Integer -> Integer -> Bool
divides d n = rem n d == 0

ld :: Integer -> Integer
ld n = ldf 2 n

ldf :: Integer -> Integer -> Integer
ldf k n 
 | divides k n = k
 | k^2 > n = n
 | otherwise = ldf (k+1) n

factors :: Integer -> [Integer]
factors n 
 | n == 1 = []
 | otherwise = p : factors (div n p) 
 	where p = ld n
 
main :: IO()
main = print ( factors ( foldl (+) 0 ( seq357n 375 ) ) )