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 A141889 #12 Sep 08 2022 08:45:35 %S A141889 67,109,151,193,277,487,571,613,739,823,907,991,1033,1117,1201,1327, %T A141889 1453,1579,1621,1663,1747,1789,1831,1873,1999,2083,2251,2293,2377, %U A141889 2503,2671,2713,2797,3049,3217,3259,3301,3343,3469,3511,3637,3847,3889,3931,4057 %N A141889 Primes congruent to 4 mod 21. %H A141889 Vincenzo Librandi, <a href="/A141889/b141889.txt">Table of n, a(n) for n = 1..1000</a> %F A141889 a(n) ~ 12n log n. - _Charles R Greathouse IV_, Jul 03 2016 %t A141889 Select[Range[4,5000,21],PrimeQ] (* _Vladimir Joseph Stephan Orlovsky_, Apr 03 2011*) %o A141889 (Magma) [p: p in PrimesUpTo(6000) | p mod 21 eq 4 ]; // _Vincenzo Librandi_, Aug 16 2012 %o A141889 (PARI) is(n)=isprime(n) && n%21==4 \\ _Charles R Greathouse IV_, Jul 03 2016 %Y A141889 Cf. A000040, A124826. %K A141889 nonn,easy %O A141889 1,1 %A A141889 _N. J. A. Sloane_, Jul 11 2008