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A000979
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Wagstaff primes: primes of form (2^p + 1)/3.
(Formerly M2896 N1161)
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26
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3, 11, 43, 683, 2731, 43691, 174763, 2796203, 715827883, 2932031007403, 768614336404564651, 201487636602438195784363, 845100400152152934331135470251, 56713727820156410577229101238628035243, 62357403192785191176690552862561408838653121833643
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OFFSET
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1,1
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COMMENTS
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Also, the primes with prime indices in the Jacobsthal sequence A001045.
Indices n such that (2^n + 1)/3 is prime are listed in A000978. - Alexander Adamchuk, Oct 03 2006
Primes in A126614. - Omar E. Pol, Nov 05 2013
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REFERENCES
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N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..20
C. Caldwell's The Top Twenty, Wagstaff.
Editor's Note, Table of Wagstaff primes sent by D. H. Lehmer, Math. Mag., 27 (1954), 156-157.
Editor's Note, Table of Wagstaff primes sent by D. H. Lehmer (annotated and scanned copy)
S. S. Wagstaff, Jr., The Cunningham Project.
Wikipedia, Wagstaff prime
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MATHEMATICA
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Select[ Array[(2^# + 1)/3 &, 190], PrimeQ] (* Vladimir Joseph Stephan Orlovsky, Apr 03 2010 *)
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PROG
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(Haskell)
a000979 n = a000979_list !! (n-1)
a000979_list = filter ((== 1) . a010051) a007583_list
-- Reinhard Zumkeller, Mar 24 2013
(Python)
from gmpy2 import divexact
from sympy import prime, isprime
A000979 = [p for p in (divexact(2**prime(n)+1, 3) for n in range(2, 10**2)) if isprime(p)] # Chai Wah Wu, Sep 04 2014
(PARI) forprime(p=2, 10000, if(ispseudoprime(2^p\/3), print1(2^p\/3, ", "))) \\ Edward Jiang, Sep 05 2014
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CROSSREFS
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Cf. A000978, A049883, A001045, A127962.
Cf. A010051; subsequence of A007583.
Sequence in context: A051257 A135482 A126614 * A123628 A153476 A107290
Adjacent sequences: A000976 A000977 A000978 * A000980 A000981 A000982
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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