A359950 - OEIS

%I #32 Mar 13 2023 02:54:32

%S 2,7,29,601,29,116929,11887,4778489,82207,296987,2767,464089,36922117,

%T 71722471217,10219277051,9406703479,2040247819,122450719,1265072927,

%U 18353142818474353,21514105057,46999724987,29693667067,5684341885088084044195811037649,692132186353,12114317049616531

%N a(n) is the greatest prime factor of n^n - n!.

%H Amiram Eldar, <a href="/A359950/b359950.txt">Table of n, a(n) for n = 2..106</a>

%F a(n) = A006530(A036679(n)) = A006530(n*A126130(n-1)).

%e a(5) = greatest prime factor of 5^5 - 5! = greatest prime factor of 3125 - 120 = greatest prime factor of 3005 = 3005/5 = 601.

%t Table[Max[First/@FactorInteger[n^n-n!]],{n,2,27}] (* _Stefano Spezia_, Jan 22 2023 *)

%o (PARI) a(n) = vecmax(factor(n^n - n!)[,1]); \\ _Michel Marcus_, Jan 22 2023

%Y Cf. A006530, A020639, A036679, A126130.

%K nonn

%O 2,1

%A _Sebastian F. Orellana_, Jan 19 2023

%E More terms from _Michel Marcus_, Jan 22 2023