This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A139874 #18 Sep 08 2022 08:45:34
%S A139874 3,59,83,131,227,251,419,467,563,587,971,1091,1259,1307,1427,1571,
%T A139874 1811,1907,1931,1979,2099,2243,2267,2411,2579,2819,2939,3083,3251,
%U A139874 3323,3491,3659,3779,3923,3947,4091,4259,4283,4451,4787,4931,5003
%N A139874 Primes of the form 3x^2 + 56y^2.
%C A139874 Discriminant = -672. See A139827 for more information.
%C A139874 Except for 3, also primes of the form 20x^2 + 12xy + 27y^2. See A140633. - _T. D. Noe_, May 19 2008
%H A139874 Vincenzo Librandi and Ray Chandler, <a href="/A139874/b139874.txt">Table of n, a(n) for n = 1..10000</a> [First 1000 terms from Vincenzo Librandi]
%H A139874 N. J. A. Sloane et al., <a href="https://oeis.org/wiki/Binary_Quadratic_Forms_and_OEIS">Binary Quadratic Forms and OEIS</a> (Index to related sequences, programs, references)
%F A139874 Except for 3, the primes are congruent to {59, 83, 131} (mod 168).
%t A139874 QuadPrimes2[3, 0, 56, 10000] (* see A106856 *)
%o A139874 (Magma) [3] cat [ p: p in PrimesUpTo(6000) | p mod 168 in {59, 83, 131}]; // _Vincenzo Librandi_, Jul 30 2012
%o A139874 (PARI) list(lim)=my(v=List(),w,t); for(x=1, sqrtint(lim\3), w=3*x^2; for(y=0, sqrtint((lim-w)\56), if(isprime(t=w+56*y^2), listput(v,t)))); Set(v) \\ _Charles R Greathouse IV_, Mar 07 2017
%K A139874 nonn,easy
%O A139874 1,1
%A A139874 _T. D. Noe_, May 02 2008