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 A004619 #18 Oct 26 2023 00:42:26
%S A004619 1,29,43,71,113,127,197,211,239,281,337,379,421,449,463,491,547,617,
%T A004619 631,659,673,701,743,757,827,841,883,911,953,967,1009,1051,1093,1163,
%U A004619 1247,1289,1303,1373,1429,1471
%N A004619 Numbers divisible only by primes congruent to 1 mod 7.
%H A004619 Vincenzo Librandi, <a href="/A004619/b004619.txt">Table of n, a(n) for n = 1..1000</a>
%t A004619 ok[1]=True;ok[n_]:=And@@(Mod[#,7]==1&)/@FactorInteger[n][[All,1]];Select[Range[6000],ok] (* _Vincenzo Librandi_, Aug 20 2012 *)
%o A004619 (Magma) [n: n in [1..2000] | forall{d: d in PrimeDivisors(n) | d mod 7 eq 1}]; // _Vincenzo Librandi_, Aug 20 2012
%o A004619 (PARI) is(n)=if(n%7!=1, return(0)); my(f=factor(n)[,1]); for(i=1,#f~, if(f[i]%7!=1, return(0))); 1 \\ _Charles R Greathouse IV_, Jul 02 2016
%K A004619 nonn,easy
%O A004619 1,2
%A A004619 _N. J. A. Sloane_