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 A032728 #16 Aug 13 2024 11:13:30
%S A032728 4,5,7,8,10,11,16,20,22,25,29,31,32,35,38,44,46,49,52,53,55,65,70,71,
%T A032728 73,76,77,88,91,92,98,101,103,106,107,113,115,118,121,124,125,131,137,
%U A032728 146,148,164,169,172,176,179,184,185,200,202,205,206,208,209,211
%N A032728 Numbers k such that k prefixed by '3' and followed by '9' is prime.
%H A032728 Harvey P. Dale, <a href="/A032728/b032728.txt">Table of n, a(n) for n = 1..1000</a>
%t A032728 Select[Range[250],PrimeQ[FromDigits[Join[{3},IntegerDigits[#],{9}]]]&] (* _Harvey P. Dale_, Aug 17 2021 *)
%Y A032728 Cf. A032702-A032733.
%K A032728 nonn,base
%O A032728 1,1
%A A032728 _Patrick De Geest_, May 15 1998
%E A032728 Offset changed by _Andrew Howroyd_, Aug 13 2024