OFFSET
1,1
COMMENTS
n!10 = product( n-10k, 0 <= k < n/10 ).
See also links in A156165.
a(1)-a(40) are proved prime by deterministic tests of pfgw. - Robert Price, Jun 11 2012
a(41) > 50000. - Robert Price, Jun 11 2012
LINKS
Ken Davis, Status of Search for Multifactorial Primes.
Ken Davis, Results for n!10-1.
MATHEMATICA
MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[1000], PrimeQ[MultiFactorial[#, 10] - 1] & ] (* Robert Price, Apr 19 2019 *)
PROG
(PARI) for(n=0, 9999, isprime(prod(i=0, (n-2)\10, n-10*i)-1)& print1(n", "))
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
M. F. Hasler, Jan 17 2012
EXTENSIONS
a(26)-a(40) from Robert Price, Jun 11 2012
a(41)-a(45) from Ken Davis link entered by Robert Price, Apr 19 2019
STATUS
approved