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 A069226 #16 Jan 15 2025 22:45:24
%S A069226 2,1,1,3,1,1,1,1,1,9,5,1,1,1,1,3,1,1,1,1,1,3,1,1,1,1,1,27,1,1,5,1,1,3,
%T A069226 1,1,1,1,1,3,1,1,1,1,1,9,1,1,1,1,25,3,1,1,1,11,1,3,1,1,1,1,1,9,1,1,1,
%U A069226 1,17,3,5,1,1,1,1,3,1,1,13,1,1,81,1,1,1,1,1,3,1,1,5,1,1,3,1,1,1,1,1,9,1
%N A069226 a(n) = gcd(n, 2^n + 1).
%C A069226 First occurrence of n: a(1)=1, a(3)=3, a(10)=5, a(9)=9, a(55)=11, a(78)=13, a(68)=17, a(50)=25, a(27)=27, a(406)=29, a(165)=33, a(666)=37, a(301)=43, a(1378)=53, a(1711)=59, a(390)=65, a(81)=81, a(3403)=83, a(2328)=97, a(495)=99, ... - _R. J. Mathar_, Dec 14 2016
%H A069226 Antti Karttunen, <a href="/A069226/b069226.txt">Table of n, a(n) for n = 0..65537</a>
%t A069226 Table[GCD[n,2^n+1],{n,100}] (* _Harvey P. Dale_, Dec 12 2012 *)
%o A069226 (PARI) A069226(n) = gcd(n, 1+(1<<n)); \\ _Antti Karttunen_, Jan 15 2025
%Y A069226 Cf. A006521 (fixed points), A014491, A049095, A049096, A060444.
%K A069226 nonn
%O A069226 0,1
%A A069226 _Vladeta Jovovic_, Apr 12 2002
%E A069226 Term a(0) = 2 prepended by _Antti Karttunen_, Jan 15 2025