OFFSET
1,2
COMMENTS
Conjecture: sequence is infinite. But there are finitely many members which are sandwiched between twin primes.
LINKS
Robert Israel, Table of n, a(n) for n = 1..28
FORMULA
EXAMPLE
2 is in the sequence because 2 + 1 is prime.
6 is in the sequence because both 6 - 1 and 6 + 1 are prime.
24 is in the sequence because 24 - 1 is prime.
MAPLE
select(t -> isprime(t+1) or isprime(t-1), [seq(n!, n=1..100)]); # Robert Israel, Aug 25 2016
MATHEMATICA
Select[Range[32]!, Or @@ PrimeQ@ {# - 1, # + 1} &] (* Michael De Vlieger, Aug 25 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Sep 27 2003
EXTENSIONS
More terms from Ray Chandler, Sep 28 2003
STATUS
approved