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 A087368 #24 Jul 08 2024 02:21:54
%S A087368 3,5,277,353,773,3733,5557,7523,7753,25357,25733,27733,32233,32323,
%T A087368 32533,37273,53233,53353,53377,53777,55733,72337,72727,73757,77377,
%U A087368 77557,232523,272333,275773,322727,327553,327757,333233,352357,353527
%N A087368 Prime-indexed primes (PIPs) whose digits are all primes.
%C A087368 Chances are these numbers are infinite since PIPs are infinite.
%H A087368 Amiram Eldar, <a href="/A087368/b087368.txt">Table of n, a(n) for n = 1..14683</a> (terms below 10^11)
%H A087368 Albert Frank and Philippe Jacqueroux, <a href="http://www.paulcooijmans.com/others/intcontest.pdf">International Contest</a>, 2001. Item 12.
%e A087368 59 is prime, the 59th prime is 277, and 2 and 7 are primes.
%t A087368 Select[Flatten[Table[FromDigits /@ Tuples[Prime[Range[4]], k], {k, 1, 6}]], PrimeQ[#] && PrimeQ[PrimePi[#]] &] (* _Amiram Eldar_, Jul 08 2024 *)
%o A087368 (PARI) pip(n) = { for(x=1,n, flag=1; y=prime(prime(x)); y2=y; for(j=1,length(Str(y)), r = y%10; if(!isprime(r),flag=0); y = floor(y/10); ); if(flag,print1(y2",")); ) }
%Y A087368 Intersection of A006450 and A046034.
%K A087368 easy,nonn,base
%O A087368 1,1
%A A087368 _Cino Hilliard_, Oct 21 2003
%E A087368 Offset corrected by _Amiram Eldar_, Jul 08 2024