Nice primes: Difference between revisions
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Same as Wren example.
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=={{header|Haskell}}==
<syntaxhighlight lang="haskell">
import Data.Char ( digitToInt )
isPrime :: Int -> Bool
isPrime n
|n == 2 = True
|n == 1 = False
|otherwise = null $ filter (\i -> mod n i == 0 ) [2 .. root]
where
root :: Int
root = floor $ sqrt $ fromIntegral n
digitsum :: Int -> Int
digitsum n = sum $ map digitToInt $ show n
findSumn :: Int -> Int
findSumn n = until ( (== 1) . length . show ) digitsum n
isNicePrime :: Int -> Bool
isNicePrime n = isPrime n && isPrime ( findSumn n )
solution :: [Int]
solution = filter isNicePrime [501..999]</syntaxhighlight>
{{out}}
<pre>
[509,547,563,569,587,599,601,617,619,641,653,659,673,677,691,709,727,743,761,797,821,839,853,857,887,907,911,929,941,947,977,983,997]
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