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  1. sumDiv n = (+1) $
  2.            sum $
  3.            map (\x -> x + n `div` x) $
  4.            filter (\x -> n `mod` x == 0) $
  5.            takeWhile (\x -> x*x<n) [2..]
  6.  
  7. friends :: [(Int, Int)]
  8. friends = filter (\(x, s) -> x < s && sumDiv s == x) $ map (\x -> (x, sumDiv x)) [1..]
  9.  
  10. main = mapM print $ take 14 friends
Success #stdin #stdout 1.71s 3540KB
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stdin
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Standard input is empty
stdout
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(220,284)
(1184,1210)
(2620,2924)
(5020,5564)
(6232,6368)
(10744,10856)
(12285,14595)
(17296,18416)
(63020,76084)
(66928,66992)
(67095,71145)
(69615,87633)
(79750,88730)
(100485,124155)
https://ideone.com/hLrgiR
language:
Haskell (ghc 8.4.4)
created:
13 years ago
visibility:
public

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