1,3

Conjecture: 77! + 1 is the largest factorial Chen prime.

For n>2, n is in the sequence iff both numbers n!/3+1 and n!+1 are primes. - Farideh Firoozbakht, Mar 24 2006

Table of n, a(n) for n=1..6.

Cf. A002981, A109611.

Sequence in context: A301347 A241811 A155187 * A279084 A008510 A290512

Adjacent sequences: A109129 A109130 A109131 * A109133 A109134 A109135

hard,more,nonn

Jason Earls, Aug 17 2005

approved