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 A243439 #14 Nov 12 2023 12:20:38
%S A243439 29,53,107,269,2213,19709,177173,43046747,282429536507,22876792454987,
%T A243439 239299329230617529590109,19383245667680019896796749,
%U A243439 1144561273430837494885949696453,969773729787523602876821942164080815560187
%N A243439 Primes of the form 3^k + 26.
%H A243439 Vincenzo Librandi, <a href="/A243439/b243439.txt">Table of n, a(n) for n = 1..27</a>
%F A243439 a(n) = 3^A219044(n) + 26. - _Elmo R. Oliveira_, Nov 12 2023
%t A243439 Select[Table[3^n + 26, {n, 0, 500}], PrimeQ]
%o A243439 (Magma) [a: n in [0..200] | IsPrime(a) where a is 3^n+26];
%Y A243439 Cf. A000040, A219044 (corresponding k's).
%Y A243439 Cf. Similar sequences listed in A102903.
%K A243439 nonn
%O A243439 1,1
%A A243439 _Vincenzo Librandi_, Jun 05 2014