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 A020457 #23 Dec 09 2024 15:28:25
%S A020457 11,19,191,199,911,919,991,1999,9199,11119,19919,19991,91199,99119,
%T A020457 99191,99991,111119,111191,111919,119191,191119,191911,191999,199999,
%U A020457 911111,919111,991999,999199,1111991,1191119,1191191,1191199,1191991,1199999
%N A020457 Primes that contain digits 1 and 9 only.
%H A020457 Alois P. Heinz, <a href="/A020457/b020457.txt">Table of n, a(n) for n = 1..20000</a> (first 1000 terms from Vincenzo Librandi)
%H A020457 James Maynard and Brady Haran, <a href="https://www.youtube.com/watch?v=eeoBCS7IEqs">Primes without a 7</a>, Numberphile video (2019)
%t A020457 Flatten[Table[Select[FromDigits/@Tuples[{1,9},n],PrimeQ],{n,7}]] (* _Vincenzo Librandi_, Jul 27 2012 *)
%o A020457 (Magma) [p: p in PrimesUpTo(1199999) | Set(Intseq(p)) subset [1, 9]]; // _Vincenzo Librandi_, Jul 27 2012
%Y A020457 Subsequence of A329761 and hence of A030096.
%K A020457 nonn,base
%O A020457 1,1
%A A020457 _David W. Wilson_