OFFSET
1,1
COMMENTS
Primes represented by the quadratic form 4x^2 + 2xy + 7y^2, whose discriminant is -108. - T. D. Noe, May 17 2005
LINKS
Klaus Brockhaus, Table of n, a(n) for n=1..1000
Steven R. Finch, Powers of Euler's q-Series, (arXiv:math.NT/0701251), 2007.
EXAMPLE
A cube modulo 7 can only be 0, 1 or 6, but not 2, hence the prime 7 is in the sequence.
Because x^3 = 2 mod 11 when x = 7 mod 11, the prime 11 is not in the sequence.
MATHEMATICA
insolublePrimeQ[p_]:= Reduce[Mod[x^3 - 2, p] == 0, x, Integers] == False; Select[Prime[Range[200]], insolublePrimeQ] (* Vincenzo Librandi Sep 17 2012 *)
PROG
(Magma) [ p: p in PrimesUpTo(937) | forall(t){x : x in ResidueClassRing(p) | x^3 ne 2} ]; // Klaus Brockhaus, Dec 05 2008
(PARI) forprime(p=2, 10^3, if(#polrootsmod(x^3-2, p)==0, print1(p, ", "))) \\ Joerg Arndt, Jul 16 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Klaus Brockhaus, Dec 05 2008
STATUS
approved