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A243959
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Numbers n such that n^524288+1 is prime.
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5
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OFFSET
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2,1
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COMMENTS
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Generalized Fermat primes n^(2^k)+1 for k=19.
1880370 is a member, but its position is not yet known. - Jeppe Stig Nielsen, Jan 24 2018
PrimeGrid has now tested and double checked the necessary candidates to prove that 1880370 is a(5). - Jeppe Stig Nielsen, Feb 20 2018
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LINKS
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Table of n, a(n) for n=2..6.
C. Caldwell, The largest known primes (Primes with 600,000 or more digits)
H. Dubner and Y. Gallot, Distribution of generalized Fermat prime numbers, Math. Comp., 71 (2002), 825-832.
J. S. S. Nielsen, Generalized Fermat Primes sorted by base (See table at the bottom of the page.)
PrimeGrid, Announcement of n=75898
PrimeGrid, Announcement of n=341112
PrimeGrid, Announcement of n=356926
PrimeGrid, Announcement of n=475856
PrimeGrid, Announcement of n=1880370
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PROG
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(PARI) is(n)=isprime(n^524288+1) \\ Charles R Greathouse IV, Feb 20 2017
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CROSSREFS
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Cf. A056993, A244150.
Sequence in context: A140940 A204865 A135209 * A236807 A251470 A091294
Adjacent sequences: A243956 A243957 A243958 * A243960 A243961 A243962
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KEYWORD
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nonn,hard,more
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AUTHOR
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Felix Fröhlich, Jun 16 2014
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EXTENSIONS
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a(5) from Jeppe Stig Nielsen, Feb 20 2018
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STATUS
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approved
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