Is 1! + 11! + 300! prime?

[Joshua Zucker]

I confirm Joseph's result: 1! + 11! + 300! is indeed divisible by 2777.
Running some primality tests (of the sort that can prove a number
composite but don't necessarily prove a number prime) I find up to n =
1000 that the only candidate primes are when n = 17 18 21 42 77 85 693
845

Anyone want to look more carefully into 1! + 11! + 693! or + 845! perhaps?

But trying it up to 11! seems like it's going to be way too time-intensive...

--Joshua Zucker

On 8/12/06, Joseph Biberstine <jrbibers at indiana.edu> wrote:
> AFAICT 2777 is a factor.
>
> Jonathan Post wrote:
> > Is 1! + 11! + 300! prime? It has 602 digits, and the Alpertron calls it
> > "unknown" as to primality after half an hour on my Linux box. This is
> > the first such case I've encountered in my A! + B! + 1! primality search.
>
>