cp's OEIS Frontend

A007571 a(n) = largest prime factor of n^n + 1.

%I A007571 M1343 #44 Oct 10 2023 06:21:33
%S A007571 2,5,7,257,521,97,911,673,530713,27961,58367,2227777,79301,176597,
%T A007571 142111,67280421310721,45957792327018709121,33388093,870542161121,
%U A007571 4406613081041681,22864311556633,73194743542229,1522029233,27250359649
%N A007571 a(n) = largest prime factor of n^n + 1.
%D A007571 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A007571 Tyler Busby, <a href="/A007571/b007571.txt">Table of n, a(n) for n = 1..148</a> (terms 1..123 from Hugo Pfoertner, terms 124..135 from Yurii Ivanov)
%H A007571 factordb, <a href="http://factordb.com/index.php?query=n%5En%2B1&amp;use=n&amp;perpage=20&amp;format=1&amp;sent=1&amp;PR=1&amp;PRP=1&amp;C=1&amp;CF=1&amp;U=1&amp;FF=1&amp;VP=1&amp;EV=1&amp;OD=1&amp;VC=1&amp;n=148">Status of 148^148+1 ... 167^167+1</a>.
%F A007571 a(n) = A006530(A014566(n)). - _Michel Marcus_, Aug 24 2019
%t A007571 Table[ FactorInteger[ n^n + 1, FactorComplete -> True ] [ [ -1, 1 ] ], {n, 1, 25} ]
%o A007571 (PARI) for(k=1, 24, my(x=factor(k^k+1), f=x[#x[, 1], 1]); print1(f,", ")) \\ _Hugo Pfoertner_, Aug 23 2019
%o A007571 (Magma) [Max(PrimeDivisors(n^n+1)):n in [1..24]]; // _Marius A. Burtea_, Aug 24 2019
%Y A007571 Cf. A006530, A006486, A014566, A056790.
%K A007571 nonn,hard
%O A007571 1,1
%A A007571 _N. J. A. Sloane_, _Robert G. Wilson v_