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A243959 Numbers k such that k^524288 + 1 is prime. 5
75898, 341112, 356926, 475856, 1880370, 2061748 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

Generalized Fermat primes k^(2^j) + 1 for j=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

LINKS

Table of n, a(n) for n=2..7.

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

PrimeGrid, Announcement of n=2061748

PROG

(PARI) is(n)=isprime(n^524288+1) \\ Charles R Greathouse IV, Feb 20 2017

CROSSREFS

Cf. A056993, A244150.

Sequence in context: A140940 A204865 A135209 * A236807 A251470 A091294

Adjacent sequences:  A243956 A243957 A243958 * A243960 A243961 A243962

KEYWORD

nonn,hard,more

AUTHOR

Felix Fröhlich, Jun 16 2014

EXTENSIONS

a(5) from Jeppe Stig Nielsen, Feb 20 2018

a(6) from Jeppe Stig Nielsen, Apr 27 2018

STATUS

approved

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Last modified June 19 12:10 EDT 2018. Contains 305581 sequences. (Running on oeis4.)