OFFSET
1,1
COMMENTS
The discriminant is -192 (or 96, or ...), depending on which quadratic form is used for the definition. Binary quadratic forms a*x^2+b*x*y+c*y^2 have discriminant d=b^2-4ac and gcd(a,b,c)=1. See A107132 for more information.
REFERENCES
Z. I. Borevich and I. R. Shafarevich, Number Theory.
LINKS
Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi]
William C. Jagy and Irving Kaplansky, Positive definite binary quadratic forms that represent the same primes [Cached copy] See Table II.
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS: Index to related sequences, programs, references. OEIS wiki, June 2014.
D. B. Zagier, Zetafunktionen und quadratische Körper, Springer, 1981.
FORMULA
Except for 3, the primes are congruent to 19 (mod 24). - T. D. Noe, May 02 2008
EXAMPLE
19 is a member because we can write 19=4*2^2+4*2*1-5*1^2 (or 19=4*1^2+12*1*1+3*1^2).
MATHEMATICA
QuadPrimes2[3, 0, 16, 10000] (* see A106856 *)
PROG
(Magma) [3] cat [ p: p in PrimesUpTo(3000) | p mod 24 in {19 } ]; // Vincenzo Librandi, Jul 24 2012
(PARI) list(lim)=my(v=List(), w, t); for(x=1, sqrtint(lim\3), w=3*x^2; for(y=0, sqrtint((lim-w)\16), if(isprime(t=w+16*y^2), listput(v, t)))); Set(v) \\ Charles R Greathouse IV, Feb 09 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, May 13 2005; Laura Caballero Fernandez, Lourdes Calvo Moguer, Maria Josefa Cano Marquez, Oscar Jesus Falcon Ganfornina and Sergio Garrido Morales (oscfalgan(AT)yahoo.es), Jun 28 2008
EXTENSIONS
More terms from Colin Barker, Apr 05 2015
Edited by N. J. A. Sloane, Jul 14 2019, combining two identical entries both with multiple cross-references.
STATUS
approved