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dmalikov/pr214.hs

Created December 31, 2011 00:00
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Project Euler 214 (190s)
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pr214.hs
import PECore (eulerTotient)
import Data.Numbers.Primes
import Control.Arrow ((&&&))
eulerChains :: Integer -> Integer
eulerChains 1 = 1
eulerChains n = 1 + eulerChains (eulerTotient n)
main = print . sum . map fst . filter ( (== 25) . snd ) . map ((&&&) id eulerChains) . takeWhile (<40000000) $ primes
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