As people have posted above; probably for 2 reasons.

[*] "mirc613" is a known trojan virus that was spread to unsuspecting users several months ago.
[*] silly superstition. same reason elevators don't stop at the 13th floor. smirk

You will always find the latest version of mIRC, here.

- Raccoon

PS. Thank you Khaled. We all love v6.14 and can't wait to see what you have in store for us next!

Well. At least I won lunch.
Good philosophy, see good in bad, I like!