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 A029975 #14 Aug 11 2024 14:41:30
%S A029975 2,3,5,71,107,157,257,271,307,2549,2647,2801,3347,3697,3851,4201,4397,
%T A029975 4649,4951,5399,5651,5749,5903,6449,6701,7451,7703,8053,8501,8753,
%U A029975 9103,9551,10007,10357,10903,11057,11953,12157,12409,13109
%N A029975 Primes that are palindromic in base 7.
%H A029975 Harvey P. Dale, <a href="/A029975/b029975.txt">Table of n, a(n) for n = 1..1000</a>
%H A029975 P. De Geest, <a href="https://www.worldofnumbers.com/palpri.htm">World!Of Palindromic Primes</a>
%t A029975 f[n_]:=FromDigits[RealDigits[n,7][[1]]]==FromDigits[Reverse[RealDigits[n,7][[1]]]]; lst={}; Do[p=Prime[n]; If[f[p],AppendTo[lst,p]],{n,8!}]; lst (* _Vladimir Joseph Stephan Orlovsky_, Aug 10 2009 *)
%t A029975 pb7Q[n_]:=Module[{idn7=IntegerDigits[n,7]},idn7==Reverse[idn7]]; Select[ Prime[ Range[1600]],pb7Q] (* _Harvey P. Dale_, Nov 21 2015 *)
%K A029975 nonn,base
%O A029975 1,1
%A A029975 _Patrick De Geest_