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 A166501 #14 Mar 16 2023 10:19:41
%S A166501 3,7,31,73,79,97,313,331,349,379,397,541,571,709,739,757,769,937,967,
%T A166501 3037,3061,3067,3121,3163,3187,3217,3229,3253,3313,3319,3361,3433,
%U A166501 3457,3529,3547,3613,3631,3643,3673,3739,3769,3847,3889,5011,5023,5101,5107
%N A166501 Primes p such that (p reversed)+4 is also a prime.
%H A166501 Harvey P. Dale, <a href="/A166501/b166501.txt">Table of n, a(n) for n = 1..1000</a>
%F A166501 {p = A000040(i): A004087(i)+4 in A000040}. - _R. J. Mathar_, Oct 16 2009
%e A166501 73 is in the sequence because 37+4=41 prime.
%e A166501 331 is in the sequence because 133+4=137 prime.
%e A166501 3457 is in the sequence because 7543+4=7547 prime.
%t A166501 Select[Prime[Range[700]],PrimeQ[FromDigits[Reverse[IntegerDigits[#]]]+ 4]&] (* _Harvey P. Dale_, May 21 2012 *)
%t A166501 Select[Prime[Range[700]],PrimeQ[IntegerReverse[#]+4]&] (* _Harvey P. Dale_, Mar 16 2023 *)
%o A166501 (Magma) [p: p in PrimesUpTo(6000) | IsPrime(q+4) where q is Seqint(Reverse(Intseq(p)))]; // _Vincenzo Librandi_, Sep 15 2013
%K A166501 nonn,base,less
%O A166501 1,1
%A A166501 _Vincenzo Librandi_, Oct 15 2009
%E A166501 Keyword:base added, 3163 inserted, sequence extended by _R. J. Mathar_, Oct 16 2009