|
|
A000979
|
|
Wagstaff primes: primes of form (2^p + 1)/3.
(Formerly M2896 N1161)
|
|
26
|
|
|
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
|
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.
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
|
|
MATHEMATICA
|
Select[ Array[(2^# + 1)/3 &, 190], PrimeQ] (* 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
(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
|
|
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
|
|
|
|