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 A247683 #21 Mar 31 2021 16:05:39
%S A247683 25,115,133,169,187,205,259,295,385,403,475,493,511,529,565,583,637,
%T A247683 655,745,763,781,799,817,835,871,889,925,943,961,979,1015,1105,1141,
%U A247683 1159,1177,1195,1267,1285,1339,1357,1375,1393,1411,1465,1501
%N A247683 Odd composite numbers congruent to 7 modulo 9.
%C A247683 Subsequence of A017245 (9n + 7).
%H A247683 Odimar Fabeny, <a href="/A247683/b247683.txt">Table of n, a(n) for n = 1..10000</a>
%t A247683 Select[18Range[100] + 7, Not[PrimeQ[#]] &] (* _Alonso del Arte_, Sep 25 2014 *)
%t A247683 Select[Range[1,1501,2],CompositeQ[#]&&Mod[#,9]==7&] (* or *) Select[Range[7,1501,18],CompositeQ] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Mar 31 2021 *)
%o A247683 (PARI) lista(nn) = {forcomposite(n=1, nn, if ((n % 2) && ((n % 9) == 7), print1(n, ", ")); ); } \\ _Michel Marcus_, Sep 22 2014
%Y A247683 Cf. A017245, A247676, A247678, A247679, A247681, A247682.
%K A247683 nonn,easy
%O A247683 1,1
%A A247683 _Odimar Fabeny_, Sep 22 2014