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 A139921 #16 Sep 08 2022 08:45:34
%S A139921 3,107,131,179,251,347,419,443,467,491,563,659,971,1091,1187,1283,
%T A139921 1427,1499,1667,1811,1907,1979,2003,2027,2339,2531,2843,2939,2963,
%U A139921 3251,3299,3371,3467,3539,3779,3851,3923,4091,4211,4523,4547,4787
%N A139921 Primes of the form 3x^2+104y^2.
%C A139921 Discriminant=-1248. See A139827 for more information.
%H A139921 Vincenzo Librandi and Ray Chandler, <a href="/A139921/b139921.txt">Table of n, a(n) for n = 1..10000</a> [First 1000 terms from Vincenzo Librandi]
%H A139921 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 A139921 Except for 3, the primes are congruent to {35, 107, 131, 155, 179, 251} (mod 312).
%t A139921 QuadPrimes2[3, 0, 104, 10000] (* see A106856 *)
%o A139921 (Magma) [3] cat [ p: p in PrimesUpTo(6000) | p mod 312 in [35, 107, 131, 155, 179, 251]]; // _Vincenzo Librandi_, Aug 01 2012
%K A139921 nonn,easy
%O A139921 1,1
%A A139921 _T. D. Noe_, May 02 2008