OFFSET
1,1
COMMENTS
n!8 = A114800(n).
See also links in A156165.
For odd k, n!k +- 2 is even for all n > k and thus cannot be prime.
a(62) > 50000. - Robert Price, Aug 27 2012
The first 10 associated primes: 2, 3, 5, 7, 31, 103, 151, 3823, 16927, 126223. - Robert Price, Mar 10 2017
a(72) > 10^5. - Robert Price, Apr 24 2017
LINKS
C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75
Ken Davis, Status of Search for Multifactorial Primes.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[4, 50000], PrimeQ[MultiFactorial[#, 8] - 2] &] (* Robert Price, Mar 10 2017 *)
PROG
(PARI) for(n=0, 9999, isprime(prod(i=0, (n-2)\8, n-8*i)-2)& print1(n", "))
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
M. F. Hasler, Jan 17 2012
EXTENSIONS
a(46)-a(61) from Robert Price, Aug 27 2012
a(62)-a(71) from Robert Price, Apr 24 2017
STATUS
approved