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A109132 Numbers n such that n! + 1 is a Chen prime. n! + 1 is then called a factorial Chen prime. 0
0, 1, 2, 3, 11, 77 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

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

LINKS

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

CROSSREFS

Cf. A002981, A109611.

Sequence in context: A301347 A241811 A155187 * A279084 A008510 A290512

Adjacent sequences:  A109129 A109130 A109131 * A109133 A109134 A109135

KEYWORD

hard,more,nonn

AUTHOR

Jason Earls, Aug 17 2005

STATUS

approved

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Last modified June 4 03:18 EDT 2020. Contains 334812 sequences. (Running on oeis4.)