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 A006486 M2938 #42 Sep 08 2022 08:44:34
%S A006486 3,13,17,71,43,4733,241,757,9091,1806113,20593,1803647,8108731,
%T A006486 39225301,6700417,2699538733,465841,109912203092239643840221,222361,
%U A006486 227633407,285451051007,1920647391913,1134793633,50150933101,3574533119,12557612956332313,1100860153
%N A006486 a(n) = largest prime factor of n^n - 1.
%D A006486 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006486 <a href="/A006486/b006486.txt">Table of n, a(n) for n = 2..138</a>
%H A006486 D. S. Kluk and N. J. A. Sloane, <a href="/A002050/a002050_3.pdf">Correspondence, 1979</a>.
%F A006486 a(n) = A006530(A048861(n)). - _Michel Marcus_, Aug 24 2019
%t A006486 Table[Max@Transpose[FactorInteger[n^n - 1]][[1]], {n, 2, 28}] (* _Arkadiusz Wesolowski_, Aug 06 2012 *)
%o A006486 (PARI) for(k=2, 28, my(x=factor(k^k-1), f=x[#x[, 1], 1]); print1(f,", ")) \\ _Hugo Pfoertner_, Aug 23 2019
%o A006486 (Magma) [Max(PrimeDivisors(n^n-1)):n in [2..28]]; // _Marius A. Burtea_, Aug 24 2019
%Y A006486 Cf. A006530, A007571, A048861, A125135.
%K A006486 nonn,hard
%O A006486 2,1
%A A006486 Dennis S. Kluk (mathemagician(AT)ameritech.net)
%E A006486 Corrected by _T. D. Noe_, Nov 14 2006
%E A006486 5 more terms from _Arkadiusz Wesolowski_, Aug 06 2012
%E A006486 Terms up to a(126) in b-file added by _Sean A. Irvine_, Apr 25 2017
%E A006486 Terms a(127)-a(138) in b-file added by _Max Alekseyev_, Aug 26 2021