OFFSET
1,1
COMMENTS
No additional terms up to k=1000. - Harvey P. Dale, Oct 29 2016
EXAMPLE
For k = 4, 4!*4!! - 1 = 24*8 - 1 = 191 is prime.
MATHEMATICA
lst={}; Do[If[PrimeQ[n!*n!!-1], AppendTo[lst, n]], {n, 500}]; lst
Select[Range[200], PrimeQ[#!#!!-1]&] (* Harvey P. Dale, Oct 29 2016 *)
PROG
(Magma) a:=func< n | Factorial(n)*(&*[n..2 by -2])-1 >; [ n: n in [0..660] | IsPrime(a(n)) ]; // Bruno Berselli, Dec 19 2011
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Michel Lagneau, Dec 19 2011
EXTENSIONS
a(13) from Michael S. Branicky, Jun 17 2023
a(14) from Michael S. Branicky, Aug 13 2024
STATUS
approved