A100857 - OEIS

%I #16 Jul 08 2023 15:48:25

%S 3,5,29,727,3628811,6599,6385271,1291883,315389197,123662437024088191,

%T 2107707330310062524424576119,50717732086848522419,

%U 14602944428087660261,55353784249983832172137,16166897314580017

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

%H Amiram Eldar, <a href="/A100857/b100857.txt">Table of n, a(n) for n = 1..24</a> (using factordb.com)

%H Dario A. 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=97%2B96%21">Status of 97+96!</a>.

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

%F a(n) > A000040(n).

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

%t FactorInteger[(#-1)!+#][[-1,1]]&/@Prime[Range[15]] (* _Harvey P. Dale_, Jul 23 2011 *)

%Y Cf. A006530, A100856, A100858.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Nov 20 2004