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 A066408 Numbers n such that the Eisenstein integer (1 - ω)^n - 1 has prime norm, where ω = -1/2 + sqrt(-3)/2. 8
 2, 5, 7, 11, 17, 19, 79, 163, 193, 239, 317, 353, 659, 709, 1049, 1103, 1759, 2029, 5153, 7541, 9049, 10453, 23743, 255361, 534827, 2237561 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Analog of Mersenne primes in Eisenstein integers. The norm of a + b * ω is (a + b * ω) * (a + b * ω^2) = a^2 + a*b + b^2. Indices for which the Eisenstein-Mersenne numbers are primes. The p-th Eisenstein-Mersenne number can be written as 3^p - Legendre(3, p) * 3^((p + 1)/2) + 1. Note the enormous gap between 23743 and 255361. A modified version of Chris Nash's PFGW program was used to find the last term. - Jeroen Doumen (doumen(AT)win.tue.nl), Oct 31 2002 Let q be the integer quaternion (3 + i + j + k)/2. Then q^n - 1 is a quaternion prime for these n; that is, the norm of q^n - 1 is a rational prime. - T. D. Noe, Feb 02 2005 The actual norms also belong to the class of Generalized Unique primes (see Links section), that is primes which have a period of expansion of 1/p (in some general, non-decimal system) that it shares with no other prime. - Serge Batalov, Mar 29 2014 Next term > 2300000. - Serge Batalov, Mar 29 2014 REFERENCES P. H. T. Beelen, Algebraic geometry and coding theory, Ph.D. Thesis, Eindhoven, The Netherlands, September 2001. J. M. Doumen, Ph.D. Thesis, Eindhoven, The Netherlands, to appear. Mike Oakes, posting to primenumbers(AT)yahoogroups.com, Dec 24 2001 LINKS Pedro Berrizbeitia and Boris Iskra, Gaussian Mersenne and Eisenstein Mersenne primes, Mathematics of Computation 79 (2010), pp. 1779-1791. Chris Caldwell, The largest known primes Chris Caldwell, Generalized Unique primes Mike Oakes, Eisenstein Mersenne and Fermat primes Mike Oakes, A new series of Mersenne-like Gaussian primes Mike Oakes, Posting to the Number Theory list, Dec 27 2005 K. Pershell and L. Huff, Mersenne Primes in Imaginary Quadratic Number Fields, (2002). Eric Weissteins's World of Mathematics, Eisenstein Integer EXAMPLE For n = 7, (1 - ω)^7 - 1 has norm 2269, a prime. Or, for p = 7, 3^7 + 3^4 + 1 = 2269, which is prime. MATHEMATICA maxPi = 3000; primeNormQ[p_] := PrimeQ[1 + 3^p - 2*3^(p/2)*Cos[(p*Pi)/6]]; A066408 = {}; Do[ If[primeNormQ[p = Prime[k]], Print[p]; AppendTo[A066408, p]], {k, 1, maxPi}]; A066408 (* Jean-François Alcover, Oct 21 2011 *) PROG (PARI) print1("2, "); /*the only even member; it is special*/ forprime(n=3, 2029, if(ispseudoprime(3^n-kronecker(3, n)*3^((n+1)/2)+1), print1(n, ", "))) \\ Serge Batalov, Mar 29 2014 CROSSREFS The actual norms are in A066413. Cf. A000043, A057429. Sequence in context: A265761 A023213 A162575 * A142352 A290012 A062044 Adjacent sequences:  A066405 A066406 A066407 * A066409 A066410 A066411 KEYWORD nonn,nice,hard,more AUTHOR Mike Oakes, Dec 24 2001 EXTENSIONS a(26) from Serge Batalov, Mar 29 2014 Corrected link to NMBRTHRY posting. - Serge Batalov, Apr 01 2014 STATUS approved

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Last modified June 20 09:27 EDT 2019. Contains 324234 sequences. (Running on oeis4.)