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Sequence: smallest number greater than previous term with exactly n divisors: Difference between revisions

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Sequence: smallest number greater than previous term with exactly n divisors (view source)

Revision as of 13:56, 18 July 2020

20 bytes added ,  3 years ago
m
→‎{{header|Haskell}}
Line 329:
sequence_A069654 :: [(Int,Int)]
sequence_A069654 = go 1 $ (,) <*> countDivisors <$> [1..]
where go t ((n,c):xs) | c == t = (t,n):go (succ t) xs
where
go t ((n,c):xs) | c == t | otherwise = (t,n):go (succ t) xs
countDivisors n = foldr f 0 [1..floor $ sqrt $ realToFrac | otherwise = go t xsn]
where f x r | n `mod` x == 0 = if n `div` x == x then r+1 else r+2▼
countDivisors n = foldr f 0 [1..floor $ sqrt $ realToFrac n]
| otherwise = r▼
where
▲ f x r | n `mod` x == 0 = if n `div` x == x then r+1 else r+2
▲ | otherwise = r
 
main :: IO ()
main = mapM_ (uncurry( $ printf "a(%2d)=%5d\n")) $ take 15 sequence_A069654</lang>
{{out}}
<pre>a( 1)= 1
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