A107148 Primes of the form 2x^2 + 21y^2.

2, 23, 29, 53, 71, 149, 191, 197, 239, 263, 317, 359, 389, 431, 557, 599, 653, 701, 743, 821, 863, 911, 1031, 1061, 1103, 1229, 1367, 1373, 1439, 1493, 1583, 1607, 1709, 1733, 1871, 1877, 1901, 1997, 2039, 2069, 2087, 2111, 2207, 2213, 2237

Offset

1,1

Comments

Discriminant = -168. See A107132 for more information.

Links

Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi]

N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)

Formula

The primes are congruent to {2, 23, 29, 53, 71, 95, 149} (mod 168). - T. D. Noe, May 02 2008

Mathematica

QuadPrimes2[2, 0, 21, 10000] (* see A106856 *)

Prog

(Magma) [ p: p in PrimesUpTo(3000) | p mod 168 in {2, 23, 29, 53, 71, 95, 149} ]; // Vincenzo Librandi, Jul 24 2012
(PARI) list(lim)=my(v=List([2]), s=[23, 29, 53, 71, 95, 149]); forprime(p=23, lim, if(setsearch(s, p%168), listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Feb 09 2017

Crossrefs

Cf. A139827.

Sequence in context: A255564 A034843 A084373 * A062653 A208272 A306086

Adjacent sequences: A107145 A107146 A107147 * A107149 A107150 A107151

Keyword

nonn,easy

Author

T. D. Noe, May 13 2005

Status

approved