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tron1point0/factor.hs

Created April 24, 2012 14:56
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factor.hs
npto :: (Integral a) => a -> [a]
npto x = [2,3] ++ concat [[x*6-1,x*6+1] | x <- [1..n]]
where n = ((+1) . round . sqrt . fromIntegral $ x) `div` 6
factors :: (Integral a) => a -> [a]
factors 1 = []
factors x = least : factors (x `div` least)
where least = head $ fs ++ [x]
fs = filter ((==0) . mod x) . npto $ x
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