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 A068955 #23 Feb 06 2020 08:18:27 %S A068955 3,23,229,151,431,776887,14731,109,80317,275311670611,19395030961, %T A068955 10423708597,968299894201,19428121,165218809021364149, %U A068955 808793517812627212561,3979203955386313,588489604729898953429,2126173979464312447783,5043293621028391,90772326303985278570534379 %N A068955 Greatest prime factor of n^n - (n-1)^(n-1). %H A068955 Daniel Suteu and Amiram Eldar, <a href="/A068955/b068955.txt">Table of n, a(n) for n = 2..86</a> (terms 2..62 from Daniel Suteu) %F A068955 a(n) = A006530(A007781(n-1)). %e A068955 A007781(14) = 10809131718965763 = 3 * 61^2 * 968299894201, therefore a(14) = 968299894201. %p A068955 a:= n-> max(map(i-> i[1], ifactors(n^n-(n-1)^(n-1))[2])): %p A068955 seq(a(n), n=2..23); # _Alois P. Heinz_, Mar 10 2019 %t A068955 a[n_] := FactorInteger[n^n - (n-1)^(n-1)][[-1, 1]]; Array[a, 20, 2] (* _Amiram Eldar_, Feb 06 2020 *) %o A068955 (PARI) a(n) = vecmax(factor(n^n-(n-1)^(n-1))[,1]); \\ _Daniel Suteu_, Mar 10 2019 %Y A068955 Cf. A006530, A007781, A068954, A068956. %K A068955 nonn %O A068955 2,1 %A A068955 _Reinhard Zumkeller_, Mar 11 2002 %E A068955 a(18)-a(22) from _Daniel Starodubtsev_, Mar 10 2019