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 A104066 #20 Nov 08 2023 06:51:03
%S A104066 11,23,71,263,1031,65543,262151,1048583,268435463,1073741831,
%T A104066 274877906951,17592186044423,302231454903657293676551,
%U A104066 309485009821345068724781063,316912650057057350374175801351
%N A104066 Primes of the form 2^k + 7.
%C A104066 Also primes of the form 4^n+7 (in this case, the associated n are in A217349). - _Bruno Berselli_, Oct 03 2012
%F A104066 a(n) = 2^A057195(n) + 7. - _Elmo R. Oliveira_, Nov 08 2023
%t A104066 a = Delete[Union[Flatten[Table[If [PrimeQ[2^n + 7] == True, 2^ n + 7, 0], {n, 1, 400}]]], 1]
%o A104066 (Magma) [a: n in [0..100 by 2] | IsPrime(a) where a is 2^n+7]; // _Vincenzo Librandi_, Jan 26 2011
%o A104066 (PARI) list(lim)=my(v=List(),t); for(n=1,logint(lim\1-7,4), if(ispseudoprime(t=4^n+7), listput(v,t))); Vec(v) \\ _Charles R Greathouse IV_, Nov 17 2017
%Y A104066 Cf. A000040, A057195 (numbers k such that 2^k + 7 is prime).
%K A104066 nonn
%O A104066 1,1
%A A104066 _Roger L. Bagula_, Mar 02 2005