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A139848 Primes of the form 7x^2 + 15y^2. 1
7, 43, 67, 127, 163, 463, 487, 547, 823, 883, 907, 967, 1087, 1303, 1327, 1423, 1663, 1723, 1747, 2083, 2143, 2347, 2503, 2647, 2683, 2767, 3067, 3187, 3343, 3607, 3823, 3847, 3907, 3943, 4027, 4243, 4327, 4363, 4447, 4603, 4663, 4783, 5023 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Discriminant = -420. See A139827 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 {7, 43, 67, 127, 163, 247, 403} (mod 420).

MATHEMATICA

QuadPrimes2[7, 0, 15, 10000] (* see A106856 *)

PROG

(MAGMA) [ p: p in PrimesUpTo(6000) | p mod 420 in {7, 43, 67, 127, 163, 247, 403}]; // Vincenzo Librandi, Jul 29 2012

(PARI) list(lim)=my(v=List([7]), s=[43, 67, 127, 163, 247, 403]); forprime(p=43, lim, if(setsearch(s, p%420), listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Feb 10 2017

CROSSREFS

Sequence in context: A176252 A118703 A139832 * A052029 A168026 A142102

Adjacent sequences:  A139845 A139846 A139847 * A139849 A139850 A139851

KEYWORD

nonn,easy

AUTHOR

T. D. Noe, May 02 2008

STATUS

approved

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Last modified April 4 21:43 EDT 2020. Contains 333238 sequences. (Running on oeis4.)