

A057429


Numbers n such that (1+i)^n  1 times its conjugate is prime.


10



2, 3, 5, 7, 11, 19, 29, 47, 73, 79, 113, 151, 157, 163, 167, 239, 241, 283, 353, 367, 379, 457, 997, 1367, 3041, 10141, 14699, 27529, 49207, 77291, 85237, 106693, 160423, 203789, 364289, 991961, 1203793, 1667321, 3704053, 4792057
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OFFSET

1,1


COMMENTS

Equivalently, numbers n such that (1+i)^n  1 is a Gaussian prime.
Note that n must be a rational prime. Also note that (1+i)^n + i or (1+i)^n  i is also a Gaussian prime.  T. D. Noe, Jan 31 2005
Primes which are the norms of the Gaussian integers (1 + i)^n  1 or (1  i)^n  1.  Jonathan Vos Post, Feb 05 2010
Let z = (1+i)^n  1. The product of z and its conjugate is 1 + 2^n  cos(n*Pi/4)*2^(1+n/2). For n > 3, the primes are in A007670 or A007671 depending on whether n = {1, 7} (mod 8) or n = {3, 5} (mod 8), respectively.  T. D. Noe, Mar 07 2010
Primes p such that ((1+i)^p  1)((1i)^p  1) is prime. Number 2 together with odd primes p such that the norm 2^p  (1)^((p^21)/8)*2^((p+1)/2) + 1 is prime. Note that Legendre symbol (2/p) = (1)^((p^21)/8) as above.  Thomas Ordowski, Feb 20 2013
I have found that 4792057 is a term in the sequence but I can't yet confirm its position in the sequence.  Serge Batalov, Apr 05 2014
The exhaustive search for all a(n)<5000000 is now complete.  Serge Batalov, Sep 06 2014
The primes generated by these series are also generalized unique primes. They can be represented as Phi(4, 2^((p+1)/2)  (2/p))/2, where (2/p) is the Legendre symbol (Cf. link to Generalized unique primes page at UTM).  Serge Batalov, Sep 08 2014


REFERENCES

Mike Oakes, posting to the Mersenne list, Sep 07 2000.


LINKS

Table of n, a(n) for n=1..40.
Pedro Berrizbeitia and Boris Iskra, Gaussian Mersenne and Eisenstein Mersenne primes, Mathematics of Computation 79 (2010), pp. 17791791.
C. Caldwell, The largest known primes
C. Caldwell, Generalized unique primes
Marc Chamberland, Binary BBPFormulae for Logarithms and Generalized GaussianMersenne Primes, J. Integer Seqs., Vol. 6, 2003.
MersenneForum, Gaussian Mersenne norm project coordination
M. Oakes, A new series of Mersennelike Gaussian primes
M. Oakes, Posting to the Number Theory list, Dec 27 2005
K. Pershell and L. Huff, Mersenne Primes in Imaginary Quadratic Number Fields, (2002).
Index entries for Gaussian integers and primes


EXAMPLE

Note that 4 is not in the sequence because (1+i)^4  1 = 5, which is an integer prime, but not a Gaussian prime.


MATHEMATICA

Do[a = (1 + I)^n  1; b = a * Conjugate[a]; If[PrimeQ[b], Print[n]], {n, 1, 160426}] (* Wilson *)
Select[Range[1000], PrimeQ[((1 + I)^#  1)Conjugate[(1 + I)^#  1]] &] (* Alonso del Arte, May 01 2014 *)
Select[Range[48*10^5], PrimeQ[(1+I)^#1, GaussianIntegers>True]&] (* Harvey P. Dale, Dec 30 2018 *)


PROG

(PARI)
N=10^7; default(primelimit, N);
forprime(p=2, N, if(ispseudoprime(norm((1+I)^p1)), print1(p, ", ")));
/* Joerg Arndt, Jul 06 2011 */


CROSSREFS

Cf. A000043, A066408, A007670, A007671, A027206.
Cf. A027206 ((1+i)^n + i is a Gaussian prime), A103329 ((1+i)^n  i is a Gaussian prime).
Sequence in context: A039726 A115617 A003064 * A137814 A065726 A215161
Adjacent sequences: A057426 A057427 A057428 * A057430 A057431 A057432


KEYWORD

nonn,nice,hard,more


AUTHOR

Robert G. Wilson v, Sep 07 2000


EXTENSIONS

364289 found by Nicholas Glover on Jun 02 2001  Mike Oakes
Edited by Dean Hickerson, Aug 14 2002; revised by N. J. A. Sloane, Dec 28 2005
a(37)a(38) from B. Jaworski (found in 2006 and 2011)  Serge Batalov, May 01 2014
a(39)a(40) from Serge Batalov, Sep 06 2014


STATUS

approved



