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 A250396 #19 Oct 07 2021 01:59:11
%S A250396 3,3,5,11,19,37,67,131,269,523,1061,2053,4099,8219,16421,32771,65539,
%T A250396 131213,262147,524309,1048589,2097211,4194371,8388619,16777259,
%U A250396 33554467,67108933,134217773,268435459,536871019,1073741827,2147483659,4294967357,8589934621,17179869269,34359738421,68719476851,137438953741
%N A250396 a(n) is the smallest prime greater than 2^n such that 2 is a primitive root modulo a(n).
%D A250396 Henri Cohen, A Course in Computational Algebraic Number Theory, Springer Verlag, (1993)
%H A250396 Amiram Eldar, <a href="/A250396/b250396.txt">Table of n, a(n) for n = 0..300</a>
%H A250396 Joerg Arndt, <a href="http://www.jjj.de/fxt/#fxtbook">Matters Computational; Ideas, Algorithms, Source Code</a>, (ยง1.5.1, p.13).
%t A250396 With[{n = 20},
%t A250396 Module[{p = NextPrime[2^n]},
%t A250396 While[FreeQ[PrimitiveRootList[p], 2], p = NextPrime[p]]; p]]
%o A250396 (PARI) a(n)=forprime(p=2^n+1,,if(znorder(Mod(2,p))==p-1,return(p))); \\ _Joerg Arndt_, Nov 21 2014
%Y A250396 Cf. A104080 (smallest prime >= 2^n).
%K A250396 nonn
%O A250396 0,1
%A A250396 _Morgan L. Owens_, Nov 21 2014