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A000979 Wagstaff primes: primes of form (2^p + 1)/3.
(Formerly M2896 N1161)
25
3, 11, 43, 683, 2731, 43691, 174763, 2796203, 715827883, 2932031007403, 768614336404564651, 201487636602438195784363, 845100400152152934331135470251, 56713727820156410577229101238628035243, 62357403192785191176690552862561408838653121833643 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

REFERENCES

Editor's Note, Math. Mag., 27 (1954), 157.

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).

LINKS

T. D. Noe, Table of n, a(n) for n=1..20

C. Caldwell's The Top Twenty, Wagstaff.

S. S. Wagstaff, Jr., The Cunningham Project.

Wikipedia, Wagstaff prime

MATHEMATICA

Select[ Array[(2^# + 1)/3 &, 190], PrimeQ] [From Vladimir Joseph Stephan Orlovsky, Apr 03 2010]

PROG

(Haskell)

a000979 n = a000979_list !! (n-1)

a000979_list = filter ((== 1) . a010051) a007583_list

-- Reinhard Zumkeller, Mar 24 2013

CROSSREFS

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

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified July 26 03:04 EDT 2014. Contains 244924 sequences.