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 A069684 #36 Jul 29 2025 19:15:18
%S A069684 2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,
%T A069684 97,191,193,197,199,293,397,491,499,593,599,691,797,991,997,1993,1997,
%U A069684 1999,2999,4993,4999,6991,6997,7993,8999,19991,19993,19997,49991,49993,49999
%N A069684 Primes with either no internal digits or all internal digits are 9.
%H A069684 Harvey P. Dale, <a href="/A069684/b069684.txt">Table of n, a(n) for n = 1..252</a> (All terms with less than 500 digits.)
%t A069684 Join[Prime[Range[25]],Select[Flatten[Table[FromDigits[Join[{d1},PadRight[{},n,9],{d2}]],{n,150},{d1,9},{d2,{1,3,7,9}}]],PrimeQ]] (* _Harvey P. Dale_, Nov 10 2024 *)
%t A069684 Join[Prime[Range[25]],Select[Prime[Range[26,5200]],Union[Most[Rest[IntegerDigits[#]]]]=={9}&]] (* _Harvey P. Dale_, Jul 29 2025 *)
%Y A069684 Cf. A069675, A069676, A069677, A069678, A069679, A069680, A069681, A069682, A069683.
%K A069684 nonn,base
%O A069684 1,1
%A A069684 _Amarnath Murthy_, Apr 06 2002
%E A069684 Corrected by _Ray Chandler_, Nov 24 2003
%E A069684 Offset corrected and name changed by _Arkadiusz Wesolowski_, Sep 07 2011