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 A063271 #22 May 26 2022 13:16:55
%S A063271 2,41,193,6481,21523361,42521761,769,647753,926510094425921,
%T A063271 282429005041,128653413121,56625998353,24127552321,37644053098601,
%U A063271 36214795668330833,42521761,1716841910146256242328924544641,3833564416504313,56227703611393,278733912072436804273
%N A063271 Largest prime factor of 9^(2n)+1 (A063270).
%H A063271 Daniel Suteu and Harry J. Smith, <a href="/A063271/b063271.txt">Table of n, a(n) for n = 0..172</a> (terms a(0)..a(50) from Harry J. Smith)
%F A063271 a(n) = A006530(A063270(n)) = A002592(2*n) = A074476(4*n). - _Daniel Suteu_, May 26 2022
%t A063271 Table[FactorInteger[9^(2n)+1][[-1,1]],{n,0,20}] (* _Harvey P. Dale_, Jan 07 2013 *)
%o A063271 (PARI) a(n)={vecmax(factor(9^(2*n) + 1)[,1])} \\ _Harry J. Smith_, Aug 20 2009
%Y A063271 Cf. A006530, A063270, A074476, A002592.
%K A063271 nonn
%O A063271 0,1
%A A063271 _Jason Earls_, Jul 12 2001
%E A063271 Definition corrected by _Harry J. Smith_, Aug 20 2009