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 A274905 #37 Feb 25 2023 17:10:11
%S A274905 2,3,13,19,241,331,109,5419,673,87211,1321,20857,38737,22366891,14449,
%T A274905 18837001,22253377,43691,279073,160465489,4562284561,77158673929,
%U A274905 4327489,168749965921,487824887233,1133836730401,21841,272010961,88959882481,96076791871613611
%N A274905 Largest prime factor of 8^n + 1.
%H A274905 <a href="/A274905/b274905.txt">Table of n, a(n) for n = 0..502</a>
%H A274905 J. Brillhart et al., <a href="http://dx.doi.org/10.1090/conm/022">Factorizations of b^n +- 1</a>, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
%F A274905 a(n) = A006530(A062395(n)). - _Michel Marcus_, Jul 11 2016
%F A274905 a(n) = A002587(3*n). - _Amiram Eldar_, Feb 02 2020
%p A274905 8^4 + 1 = 4097 = 17*241, so a(4) = 241.
%t A274905 Table[FactorInteger[8^n + 1][[-1, 1]], {n, 0, 40}]
%o A274905 (Magma) [Maximum(PrimeDivisors(8^n+1)): n in [0..40]];
%Y A274905 Cf. A002587, A006530, A062395.
%Y A274905 Cf. similar sequences listed in A274903.
%K A274905 nonn
%O A274905 0,1
%A A274905 _Vincenzo Librandi_, Jul 11 2016
%E A274905 Terms to a(100) in b-file from _Vincenzo Librandi_, Jul 12 2016
%E A274905 a(101)-a(354) in b-file from _Amiram Eldar_, Feb 02 2020
%E A274905 a(355)-a(502) in b-file from _Max Alekseyev_, May 28 2022, Sep 06 2022, Feb 25 2023