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 A039687 #35 Mar 04 2023 02:02:44
%S A039687 7,13,97,193,769,12289,786433,3221225473,206158430209,6597069766657,
%T A039687 221360928884514619393,
%U A039687 2353913150770005286438421033702874906038383291674012942337
%N A039687 Primes of the form 3*2^k + 1.
%C A039687 Primes of the form 6m+1 (A002476) of A074781. - _Bernard Schott_, Dec 14 2020
%H A039687 S. W. Golomb, <a href="http://www.jstor.org/stable/2005337">Properties of the sequence 3*2^n+1</a>, Math. Comp., 30 (1976), 657-663.
%H A039687 S. W. Golomb, <a href="/A004119/a004119.pdf">Properties of the sequence 3*2^n+1</a>, Math. Comp., 30 (1976), 657-663. [Annotated scanned copy]
%H A039687 Ernest G. Hibbs, <a href="https://www.proquest.com/openview/4012f0286b785cd732c78eb0fc6fce80">Component Interactions of the Prime Numbers</a>, Ph. D. Thesis, Capitol Technology Univ. (2022), see p. 33.
%F A039687 a(n) = 3*2^A002253(n) + 1. - _M. F. Hasler_, Mar 03 2023
%t A039687 Select[Table[6 2^n+1,{n,0,250}],PrimeQ] (* _Harvey P. Dale_, Dec 17 2010 *)
%o A039687 (PARI) A039687(n)=3<<A002253(n)+1 \\ _M. F. Hasler_, Mar 03 2023
%Y A039687 For more terms see A002253. These are the primes in A004119 (or A181565).
%Y A039687 Cf. A002476, A074781.
%Y A039687 Subsequence of A081091.
%K A039687 nonn
%O A039687 1,1
%A A039687 _Felice Russo_