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 A106861 #23 Aug 05 2014 14:16:29 %S A106861 19,31,79,109,151,181,199,211,229,271,331,349,409,421,439,499,571,601, %T A106861 619,631,661,691,709,769,811,829,859,919,991,1021,1039,1051,1069,1129, %U A106861 1171,1201,1249,1291,1321,1381,1399,1429,1459,1471,1489,1531,1579 %N A106861 Primes of the form x^2+xy+4y^2, with x and y nonnegative. %C A106861 Discriminant=-15. %C A106861 Subset of A033212. - _Robert Israel_, Jul 25 2014 %H A106861 Vincenzo Librandi and Rick L. Shepherd, <a href="/A106861/b106861.txt">Table of n, a(n) for n = 1..10000</a> (first 2000 terms from Vincenzo Librandi) %H A106861 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) %p A106861 N:= 1000; # to get all terms <= N %p A106861 Primes:= select(isprime,[seq(2*n+1,n=1..floor((N-1)/2))]): %p A106861 filter:= proc(p) local S; %p A106861 S:= remove(hastype,[isolve(x^2+x*y+4*y^2=p)],negint); %p A106861 nops(S) > 0 %p A106861 end proc: %p A106861 A:= select(filter,Primes); # _Robert Israel_, Jul 25 2014 %t A106861 QuadPrimes2[1, 1, 4, 1000000] (* see A106856 *) %Y A106861 Cf. A033212. %K A106861 nonn,easy %O A106861 1,1 %A A106861 _T. D. Noe_, May 09 2005