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 A227869 #18 Oct 09 2023 17:04:17
%S A227869 187,217,247,427,517,637,667,697,817,847,1027,1057,1147,1177,1207,
%T A227869 1267,1357,1387,1417,1477,1507,1537,1687,1717,1807,1837,1897,1927,
%U A227869 1957,2047,2077,2107,2167,2197,2227,2257,2317,2407,2497,2527,2587,2737,2827,2947,2977
%N A227869 Composite numbers congruent to 7 (mod 30).
%C A227869 Up to 4897, there are more primes than composites among the numbers of the form 7+30k, only from 4927 on, composite numbers become more frequent.
%C A227869 See A132231 for primes of that form. See also A132237 (primes = 7 or 23 (mod 30)) and A229947 (primes not = 7 or 23 (mod 30)).
%H A227869 Harvey P. Dale, <a href="/A227869/b227869.txt">Table of n, a(n) for n = 1..1000</a>
%t A227869 Select[Table[30n + 7, {n, 100}], Not[PrimeQ[#]] &] (* _Alonso del Arte_, Nov 03 2013 *)
%t A227869 Select[Range[7,3000,30],CompositeQ] (* _Harvey P. Dale_, Oct 09 2023 *)
%o A227869 (PARI) forstep(p=7,1999,30,isprime(p)||print1(p","))
%K A227869 nonn
%O A227869 1,1
%A A227869 _M. F. Hasler_, Nov 02 2013