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A050549
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Numbers k such that 47*2^k-1 is prime.
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0
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4, 14, 70, 78, 1374, 1824, 2158, 2654, 4494, 9598, 10068, 11524, 15128, 55408, 87324, 450470, 540494, 695384, 695724
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..19.
Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300
Wilfrid Keller, List of primes k.2^n - 1 for k < 300
Kosmaj, Riesel list k<300.
Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime
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MATHEMATICA
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Select[Range[1000], PrimeQ[47*2^# - 1] & ] (* Robert Price, Dec 22 2018 *)
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PROG
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(PARI) is(n)=ispseudoprime(47*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017
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CROSSREFS
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Sequence in context: A005501 A065606 A049372 * A222980 A321273 A322700
Adjacent sequences: A050546 A050547 A050548 * A050550 A050551 A050552
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KEYWORD
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hard,nonn,more
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AUTHOR
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N. J. A. Sloane, Dec 29 1999
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
a(17)-a (19) from the Wilfrid Keller link by Robert Price, Dec 22 2018
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STATUS
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approved
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