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 A274904 #29 Apr 15 2025 22:32:41
%S A274904 2,7,37,31,1297,101,97,197,98801,46441,6781,51828151,1678321,37571,
%T A274904 5030761,1950271,4709377,12690943,55117,48713705333,68754507401,
%U A274904 2527867231,863017,990000731,473896897,3655688315536801,6291946695217,883383463,81035189089
%N A274904 Largest prime factor of 6^n + 1.
%H A274904 <a href="/A274904/b274904.txt">Table of n, a(n) for n = 0..430</a>
%H A274904 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 A274904 a(n) = A006530(A062394(n)). - _Michel Marcus_, Jul 11 2016
%e A274904 6^3 + 1 = 217 = 7*31, so a(3) = 31.
%t A274904 Table[FactorInteger[6^n + 1][[-1, 1]], {n, 0, 40}]
%o A274904 (Magma) [Maximum(PrimeDivisors(6^n+1)): n in [0..40]];
%Y A274904 Cf. similar sequences listed in A274903.
%Y A274904 Cf. A006530, A062394.
%K A274904 nonn
%O A274904 0,1
%A A274904 _Vincenzo Librandi_, Jul 11 2016
%E A274904 Terms to a(100) in b-file from _Vincenzo Librandi_, Jul 12 2016
%E A274904 a(101)-a(408) in b-file from _Amiram Eldar_, Feb 02 2020
%E A274904 a(409)-a(430) in b-file from _Max Alekseyev_, Apr 25 2022, Apr 15 2025