A359950 a(n) is the greatest prime factor of n^n - n!.

2, 7, 29, 601, 29, 116929, 11887, 4778489, 82207, 296987, 2767, 464089, 36922117, 71722471217, 10219277051, 9406703479, 2040247819, 122450719, 1265072927, 18353142818474353, 21514105057, 46999724987, 29693667067, 5684341885088084044195811037649, 692132186353, 12114317049616531

Offset: 2

Author

Sebastian F. Orellana, Jan 19 2023

Keywords

• nonn

Examples

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

Links

• Amiram Eldar, Table of n, a(n) for n = 2..106

Crossrefs

Cf. A006530, A020639, A036679, A126130.

Programs

Mathematica

Table[Max[First/@FactorInteger[n^n-n!]],{n,2,27}] (* Stefano Spezia, Jan 22 2023 *)

PARI

a(n) = vecmax(factor(n^n - n!)[,1]); \\ Michel Marcus, Jan 22 2023

Formula

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

Extensions

More terms from Michel Marcus, Jan 22 2023