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 A075240 #17 May 23 2021 02:50:53
%S A075240 2,3,11,5,13,7,11,29,19,11,19,13,29,23,19,17,23,19,31,29,29,23,29,37,
%T A075240 37,29,31,29,43,31,37,37,59,59,43,37,41,59,43,41,59,43,47,47,53,47,59,
%U A075240 61,59,61,59,53,67,59,59,59,61,59,73,61,71,67,79,71,89,67,71,101,89
%N A075240 Smallest prime whose base-n reversal is not a prime.
%C A075240 All primes show up in the sequence eventually.
%H A075240 Amiram Eldar, <a href="/A075240/b075240.txt">Table of n, a(n) for n = 2..10000</a>
%e A075240 11_10 = 23_4, reverse(23) = 32, 32_4 = 14_10, so a(4) = 11 since this does not work for smaller primes.
%t A075240 a = {}; Do[k = 1; While[ PrimeQ[ FromDigits[ Reverse[ IntegerDigits[ Prime[k], n]], n]], k++ ]; a = Append[a, Prime[k]], {n, 2, 70}]; a
%o A075240 (PARI) a(n) = my(p=2); while (isprime(fromdigits(Vecrev(digits(p, n)), n)), p = nextprime(p+1)); p; \\ _Michel Marcus_, Mar 28 2021
%Y A075240 Cf. A075241, A075242.
%K A075240 base,easy,nonn
%O A075240 2,1
%A A075240 _Robert G. Wilson v_, Sep 09 2002