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Greatest prime factor of prime(n)^n - 1.
4

%I #36 Jul 08 2023 01:19:42

%S 2,31,5,3221,157,25646167,3833,7792003,732541,150332843,144061,

%T 17615988547,6177695707,461017351,31129845205681,

%U 361353204962363828785531,903870199,751410597400064602523400427092397,25058741,153436090543,1750258119644519

%N Greatest prime factor of prime(n)^n - 1.

%H Hugo Pfoertner and Amiram Eldar, <a href="/A069460/b069460.txt">Table of n, a(n) for n = 2..96</a> (terms 2..50 from Hugo Pfoertner)

%H Dario Alpern, <a href="https://www.alpertron.com.ar/ECM.HTM">Factorization using the Elliptic Curve Method.</a>

%H FactorDB, <a href="http://factordb.com/index.php?query=509%5E97-1">Status of 509^97-1</a>.

%F a(n) = A006530(A069459(n)).

%e A000040(9)^9 - 1 = 23^9 - 1 = 1801152661462 = 2*7*11*19*79*7792003, therefore a(9) = 7792003.

%t Table[FactorInteger[Prime[n]^n-1][[-1,1]],{n,2,30}] (* _Harvey P. Dale_, May 19 2019 *)

%Y Cf. A006530, A069459, A069463.

%K nonn

%O 2,1

%A _Reinhard Zumkeller_, Mar 24 2002

%E More terms from _Hugo Pfoertner_, May 18 2004

%E Undefined a(1) removed by _Hugo Pfoertner_, Jul 22 2019