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 A341713 #45 May 29 2023 11:38:08 %S A341713 2,3,13,21,347,1217,1267,16459,100909,342243 %N A341713 Indices of Ennesrem primes: k such that A004094(k)-1 is prime. %C A341713 Numbers k such that reverse(2^k) - 1 is prime. %C A341713 Is this sequence infinite? %H A341713 N. J. A. Sloane, <a href="https://www.youtube.com/watch?v=9ogbsh8KuEM">Exciting Number Sequences</a> (video of talk), Mar 05 2021. %e A341713 13 is a term, since 2^13 = 8192 -> 2918 -> 2917, which is prime. %o A341713 (PARI) for(n=1,10000,my(pe=fromdigits(Vecrev(digits(2^n)))-1);if(ispseudoprime(pe),print1(n,", "))) \\ _Hugo Pfoertner_, Feb 20 2021 %o A341713 (Python) %o A341713 from sympy import isprime %o A341713 def ok(k): return isprime(int(str(2**k)[::-1]) - 1) %o A341713 for k in range(1, 2*10**3): %o A341713 if ok(k): print(k, end=", ") # _Michael S. Branicky_, Feb 20 2021 %Y A341713 Cf. A000043, A004094, A057708, A341709. %K A341713 nonn,base,more %O A341713 1,1 %A A341713 _N. J. A. Sloane_, Feb 20 2021 %E A341713 a(8) from _Hugo Pfoertner_, Feb 20 2021 %E A341713 a(9) from _Hugo Pfoertner_, Mar 22 2021 %E A341713 a(10) from _Steven Charlton_, Apr 26 2021