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A175755
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Numbers with 49 divisors.
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5
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46656, 1000000, 7529536, 11390625, 85766121, 113379904, 308915776, 1291467969, 1544804416, 1838265625, 3010936384, 3518743761, 9474296896, 17596287801, 27680640625, 34296447249, 38068692544, 56800235584, 75418890625, 107918163081, 164206490176, 208422380089
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OFFSET
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1,1
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COMMENTS
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Numbers of the forms p^48 and p^6*q^6, where p and q are distinct primes.
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LINKS
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FORMULA
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Sum_{n>=1} 1/a(n) = (P(6)^2 - P(12))/2 + P(48) = 0.0000226806..., where P is the prime zeta function. - Amiram Eldar, Jul 03 2022
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EXAMPLE
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MATHEMATICA
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PROG
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(Haskell)
a175755 n = a175755_list !! (n-1)
a175755_list = m (map (^ 48) a000040_list) (map (^ 6) a006881_list) where
m xs'@(x:xs) ys'@(y:ys) | x < y = x : m xs ys'
| otherwise = y : m xs' ys
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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