29 lines
1.0 KiB
Haskell
29 lines
1.0 KiB
Haskell
import Data.List.Split ( chunksOf )
|
|
|
|
isGeneralizedCurzon :: Integer -> Integer -> Bool
|
|
isGeneralizedCurzon base n = mod ( base ^ n + 1 ) ( base * n + 1 ) == 0
|
|
|
|
solution :: Integer -> [Integer]
|
|
solution base = take 50 $ filter (\i -> isGeneralizedCurzon base i ) [1..]
|
|
|
|
printChunk :: [Integer] -> String
|
|
printChunk chunk = foldl1 (++) $ map (\i -> (take ( 4 - (length $ show i) )
|
|
$ repeat ' ' ) ++ show i ++ " ") chunk
|
|
|
|
prettyPrint :: [Integer] -> [String]
|
|
prettyPrint list = map printChunk $ chunksOf 10 list
|
|
|
|
oneThousandth :: Integer -> Integer
|
|
oneThousandth base = last $ take 950 $ filter (\i -> isGeneralizedCurzon base i )
|
|
[(last $ solution base) + 1 ..]
|
|
|
|
printBlock :: Integer -> [String]
|
|
printBlock base = ["first 50 Curzon numbers using a base of " ++ show base ++ " :"]
|
|
++ (prettyPrint $ solution base) ++ ["one thousandth at base " ++ show base ++
|
|
": " ++ (show $ oneThousandth base)] ++ [take 50 $ repeat '-']
|
|
|
|
main :: IO ( )
|
|
main = do
|
|
blocks <- return $ concat $ map (\i -> printBlock i ) [2 , 4 , 6 , 8 , 10]
|
|
mapM_ putStrLn blocks
|