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 A274908 #38 Feb 25 2023 17:11:37
%S A274908 7,7,73,13,151,73,337,241,262657,331,599479,109,121369,5419,23311,673,
%T A274908 131071,262657,1212847,1321,649657,599479,10052678938039,38737,
%U A274908 10567201,22366891,97685839,14449,9857737155463,18837001,658812288653553079,22253377
%N A274908 Largest prime factor of 8^n - 1.
%H A274908 <a href="/A274908/b274908.txt">Table of n, a(n) for n = 1..500</a>
%H A274908 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 A274908 a(n) = A006530(A024088(n)). - _Michel Marcus_, Jul 11 2016
%F A274908 a(n) = A005420(3*n). - _Robert Israel_, Jul 12 2016
%e A274908 8^5 -1 = 32767 = 7*31*151, so a(5) = 151.
%p A274908 f:= n -> max(map(t -> max(numtheory:-factorset(subs(x=2,t[1]))), factors(x^(3*n)-1)[2])):
%p A274908 map(f, [$1..120]); # _Robert Israel_, Jul 12 2016
%t A274908 Table[FactorInteger[8^n - 1][[-1, 1]], {n, 40}]
%o A274908 (Magma) [Maximum(PrimeDivisors(8^n-1)): n in [1..40]];
%Y A274908 Cf. A005420, A006530, A024088, A274905.
%Y A274908 Cf. similar sequences listed in A274906.
%K A274908 nonn
%O A274908 1,1
%A A274908 _Vincenzo Librandi_, Jul 11 2016
%E A274908 Terms to a(100) in b-file from _Vincenzo Librandi_, Jul 13 2016
%E A274908 a(101)-a(402) in b-file from _Amiram Eldar_, Feb 02 2020
%E A274908 a(403)-a(500) in b-file from _Max Alekseyev_, Apr 25 2022, Sep 11 2022, Dec 05 2022, Feb 25 2023