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A103317 Primes p such that p! - 1 is also prime. 3
3, 7, 379, 6917 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The members are the primes in A002982 (n! - 1 is prime).

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, Section A2.

LINKS

Table of n, a(n) for n=1..4.

Eric Weisstein's World of Mathematics, Factorial Prime

Index entries for sequences related to factorial numbers.

EXAMPLE

3 is prime and 3! - 1 = 5 is prime, so 3 is a member.

MATHEMATICA

Select[Prime[Range[100]], PrimeQ[#! - 1] &] (* Vladimir Joseph Stephan Orlovsky, Feb 01 2012 *)

CROSSREFS

Cf. A002982.

Sequence in context: A064774 A089689 A248701 * A104051 A128004 A281889

Adjacent sequences:  A103314 A103315 A103316 * A103318 A103319 A103320

KEYWORD

hard,more,nonn

AUTHOR

Jonathan Sondow, Jan 31 2005

STATUS

approved

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Last modified May 24 09:23 EDT 2017. Contains 286963 sequences.