Wieferich primes: Difference between revisions

=={{header|Haskell}}==

<lang haskell>isPrime :: Integer -> Bool

isPrime n

|n == 2 = True

|n == 1 = False

|otherwise = null $ filter (\i -> mod n i == 0 ) [2 .. root]

where

root :: Integer

root = toInteger $ floor $ sqrt $ fromIntegral n

isWieferichPrime :: Integer -> Bool

isWieferichPrime n = isPrime n && mod ( 2 ^ ( n - 1 ) - 1 ) ( n ^ 2 ) == 0

solution :: [Integer]

solution = filter isWieferichPrime [2 .. 5000]

main :: IO ( )

main = do

putStrLn "Wieferich primes less than 5000:"

print solution</lang>

{{out}}

<pre>Wieferich primes less than 5000:

[1093,3511]</pre>