A100857 a(n) = greatest prime factor of (prime(n) - 1)! + prime(n).

3, 5, 29, 727, 3628811, 6599, 6385271, 1291883, 315389197, 123662437024088191, 2107707330310062524424576119, 50717732086848522419, 14602944428087660261, 55353784249983832172137, 16166897314580017

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..24 (using factordb.com)

Dario A. Alpern, Factorization using the Elliptic Curve Method.

FactorDB, Status of 97+96!.

Formula

a(n) = A006530(A100856(n)).

a(n) > A000040(n).

Example

n=6: (prime(6)-1)! + prime(6) = 12! + 13 = 479001600 + 13 = 479001613 = 29*2503*6599, therefore a(6) = 6599.

Mathematica

FactorInteger[(#-1)!+#][[-1, 1]]&/@Prime[Range[15]] (* Harvey P. Dale, Jul 23 2011 *)

Crossrefs

Cf. A006530, A100856, A100858.

Sequence in context: A154552 A261463 A352913 * A100856 A100858 A215780

Adjacent sequences: A100854 A100855 A100856 * A100858 A100859 A100860

Keyword

nonn

Author

Reinhard Zumkeller, Nov 20 2004

Status

approved