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 A229767 #9 Jun 07 2022 15:20:44
%S A229767 5,5,113,37,397,1613,61,953,457,14449,30269,8101,246241,107367629,
%T A229767 384773,312709,47392381,184481113,1249,12112549,1759217765581,54001,
%U A229767 140737471578113,4981857697937,26317,1801439824104653,415878438361,525313,174877,368140581013
%N A229767 Largest prime factor of 2^(2*n+1)-2^(n+1)+1.
%C A229767 2^(2*n+1)-2^(n+1)+1 is a factor of 4^(2*n+1)+1.
%H A229767 Daniel Suteu, <a href="/A229767/b229767.txt">Table of n, a(n) for n = 1..547</a>
%e A229767 For n=5, 2^(2*n+1)-2^(n+1)+1 = 1985 = 5*397, so a(5)=397.
%o A229767 (PARI) a(n) = {f=factor(2^(2*n+1)-2^(n+1)+1); f[matsize(f)[1],1]}
%Y A229767 Cf. A092440, A207262, A229747, A229768.
%K A229767 nonn
%O A229767 1,1
%A A229767 _Colin Barker_, Sep 29 2013