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 A020463 #23 Jul 03 2025 02:34:36
%S A020463 3,7,37,73,337,373,733,773,3373,3733,7333,33377,33773,37337,77377,
%T A020463 77773,333337,333737,373777,377737,733333,733373,737773,773777,777373,
%U A020463 777737,3333373,3333773,3337333,3337777,3377377,3733333,3773377,3773773,3777377,7337333,7337777,7377373,7733377,7737337
%N A020463 Primes that contain digits 3 and 7 only.
%H A020463 Jason Bard, <a href="/A020463/b020463.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Vincenzo Librandi)
%H A020463 MathOverflow, <a href="http://mathoverflow.net/questions/117689">3-7 primes in base 10</a>
%t A020463 Flatten[Table[Select[FromDigits/@Tuples[{3,7},n],PrimeQ],{n,7}]] (* _Vincenzo Librandi_, Jul 27 2012 *)
%Y A020463 Subsequence of A030096.
%Y A020463 Cf. A143967, A020458.
%K A020463 nonn,base
%O A020463 1,1
%A A020463 _David W. Wilson_