3,3

a(A002982(n)) = 1. The existence of a solution has been checked up to n=500.

The results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019

Table of n, a(n) for n=3..87.

a(10) = 6 because 10!/6! - 1 = 5039 is prime, whereas 10!/k! - 1 is composite for k = 1..5.

Cf. A093622 largest prime of the form n!/k!-1, A002982 n!-1 is prime, A093621 smallest k>0 such that n!/k!+1 is prime.

Sequence in context: A156309 A205115 A334369 * A156025 A035556 A296086

Adjacent sequences: A093620 A093621 A093622 * A093624 A093625 A093626

nonn

Hugo Pfoertner, Apr 06 2004

a(53) corrected by Gionata Neri, Jul 18 2017

approved