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 A230375 #23 Feb 23 2021 05:23:20
%S A230375 2,3,6,7,10,11,14,15,19,22,23,26,30,31,34,35,38,39,42,43,46,47,51,55,
%T A230375 58,59,62,66,67,70,71,74,78,79,82,83,86,87,91,94,95,102,103,106,107,
%U A230375 110,111,114,115,118,119,122,123,127,130,131,134,138,139,142,143
%N A230375 Squarefree numbers congruent to 2 or 3 mod 4.
%C A230375 Also numbers such that the discriminant of the quadratic field Q(sqrt(n)) equals 4n. - _Michel Marcus_, Nov 26 2013
%C A230375 The asymptotic density of this sequence is 4/Pi^2 (A185199). - _Amiram Eldar_, Feb 23 2021
%H A230375 Colin Barker, <a href="/A230375/b230375.txt">Table of n, a(n) for n = 1..1000</a>
%H A230375 Wikipedia, <a href="http://en.wikipedia.org/wiki/Quadratic_field">Quadratic field</a>.
%t A230375 Select[Range[200],SquareFreeQ[#]&&MemberQ[{2,3},Mod[#,4]]&] (* _Harvey P. Dale_, Feb 04 2015 *)
%o A230375 (PARI) s=[]; for(n=1, 200, if(issquarefree(n) && n%4!=1, s=concat(s, n))); s
%Y A230375 Cf. A039955, A039957, A185199.
%K A230375 nonn
%O A230375 1,1
%A A230375 _Colin Barker_, Oct 17 2013