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 A335787 #14 Jul 20 2020 13:07:39
%S A335787 13,31,113,311,113131,131311,1131131,1133131,1133333,1311311,1313311,
%T A335787 1331333,1333313,3111313,3131113,3133331,3331331,3333311,11113111,
%U A335787 11131111,11311133,11313311,11331311,11333131,13131133,13133311,31111313,31311113,33111311,33113131
%N A335787 Emirps containing only the digits 1 and 3.
%H A335787 Daniel Starodubtsev, <a href="/A335787/b335787.txt">Table of n, a(n) for n = 1..10000</a>
%t A335787 Select[Flatten[Table[FromDigits[#, 10] & /@ Tuples[{1, 3}, n], {n, 8}]], # != (r = IntegerReverse[#]) && PrimeQ[#] && PrimeQ[r] &] (* _Amiram Eldar_, Jun 23 2020 after _Vincenzo Librandi_ at A032917 *)
%Y A335787 Intersection of A006567 and A032917.
%Y A335787 Subsequence of A020451.
%K A335787 nonn,base
%O A335787 1,1
%A A335787 _Daniel Starodubtsev_, Jun 23 2020