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A057472
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Numbers k such that 2*6^k - 1 is prime.
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7
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1, 2, 3, 4, 5, 12, 16, 26, 27, 36, 40, 45, 49, 52, 53, 75, 140, 150, 167, 245, 250, 755, 785, 825, 970, 1235, 1289, 1477, 1739, 1872, 1976, 1993, 2175, 4218, 7656, 10898, 13410, 13625, 15706, 33003, 44288, 45556, 48855, 60522, 62795, 98898, 118429, 153714
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OFFSET
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1,2
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COMMENTS
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a(49) > 2*10^5. - Robert Price, Jan 06 2016 [Since a(39) was missing before, this a(49) should actually be a(50). - Jianing Song, Sep 22 2018]
Numbers k such that A164559(k+1) is prime.
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LINKS
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Table of n, a(n) for n=1..48.
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MATHEMATICA
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Select[Range[1000], PrimeQ[2*6^# - 1] &] (* Giovanni Resta, May 19 2016 *)
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PROG
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(PARI) is(n)=ispseudoprime(2*6^n-1) \\ Charles R Greathouse IV, Feb 17 2017
(MAGMA) [n: n in [0..2000] |IsPrime(2*6^n - 1)]; // Vincenzo Librandi, Sep 23 2018
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CROSSREFS
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Cf. A164559.
Sequence in context: A329793 A103651 A093713 * A333390 A117577 A109849
Adjacent sequences: A057469 A057470 A057471 * A057473 A057474 A057475
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v, Sep 10 2000
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EXTENSIONS
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More terms from Pierre CAMI, Jun 16 2006
Edited by Michel Marcus, Jan 06 2012
a(41)-a(48) from Robert Price, Jan 06 2016
Missing a(39) from Pierre CAMI, May 19 2016
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STATUS
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approved
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