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 A130230 #11 Oct 23 2023 14:39:04 %S A130230 5,13,29,53,61,109,149,157,173,181,229,277,293,317,397,421,461,509, %T A130230 541,613,653,661,733,773,797,821,853,941,1013,1021,1061,1069,1093, %U A130230 1109,1117,1181,1229,1237,1277,1373,1381,1429,1453,1493,1549,1597 %N A130230 Primes p == 5 (mod 8) such that the Diophantine equation x^2 - p*y^2 = -4 has a solution in odd integers x, y. %C A130230 For the Diophantine equation x^2 - p*y^2 = -4 to have a solution in odd integers x, y we must have p == 5 (mod 8) %C A130230 Calculated using Dario Alpern's quadratic Diophantine solver, see link. %C A130230 Suggested by a discussion on the Number Theory Mailing List, circa Aug 01 2007. %H A130230 Robin Visser, <a href="/A130230/b130230.txt">Table of n, a(n) for n = 1..10000</a> %H A130230 Dario Alpern, <a href="https://www.alpertron.com.ar/QUAD.HTM">Generic two integer variable equation solver</a>. %Y A130230 Cf. A130229. %K A130230 nonn %O A130230 1,1 %A A130230 _Warut Roonguthai_, Aug 06 2007