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 A102906 #14 Nov 12 2023 16:12:31
%S A102906 29,31,37,109,271,757,59077,4782997,43046749,847288609471,
%T A102906 717897987691852588770277,58149737003040059690390197,
%U A102906 30903154382632612361920641803557,1824800363140073127359051977856583949
%N A102906 Primes of the form 3^k + 28.
%H A102906 Vincenzo Librandi, <a href="/A102906/b102906.txt">Table of n, a(n) for n = 1..23</a>
%F A102906 a(n) = 3^A219046(n) + 28. - _Elmo R. Oliveira_, Nov 12 2023
%t A102906 Select[Table[3^n+28,{n,0,1000}],PrimeQ] (* _Vincenzo Librandi_, Jul 19 2012 *)
%o A102906 (Magma) [ a: n in [0..100] | IsPrime(a) where a is 3^n+28 ]; // _Vincenzo Librandi_, Jul 19 2012
%Y A102906 Cf. A000040, A219046 (corresponding k's).
%K A102906 nonn
%O A102906 1,1
%A A102906 _Roger L. Bagula_, Mar 01 2005
%E A102906 a(1) added by _Vincenzo Librandi_, Jul 19 2012