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 A227868 #13 Sep 21 2024 19:09:58
%S A227868 143,187,203,217,247,323,413,427,473,517,533,623,637,667,697,713,803,
%T A227868 817,833,847,893,923,1027,1043,1057,1073,1133,1147,1177,1207,1253,
%U A227868 1267,1313,1343,1357,1387,1403,1417,1463,1477,1507,1537,1643
%N A227868 Composite numbers congruent to 7 or 23 (mod 30).
%C A227868 It is remarkable that up to 4913, numbers congruent to 7 or 23 (mod 30) are more frequently prime than composite.
%H A227868 Harvey P. Dale, <a href="/A227868/b227868.txt">Table of n, a(n) for n = 1..2000</a>
%t A227868 Select[Range[2000],CompositeQ[#]&&MemberQ[{7,23},Mod[#,30]]&] (* _Harvey P. Dale_, Sep 21 2024 *)
%o A227868 (PARI) for(p=1,1999,setsearch([7,23],p%30)&&!isprime(p)&&print1(p","))
%Y A227868 Cf. A132237, A229947.
%K A227868 nonn
%O A227868 1,1
%A A227868 _M. F. Hasler_, Nov 02 2013