I understand random numbers for some cases but it seems strange here. If the purpose is to encrypt real EINs then one of the built in encryption routines would be a lot easier. If the purpose is to just a placeholder then why not just a simple integer counter; how is 1,2,3 less secure by obfuscation than random numbers?

PS - The guy with the table arrangement problem sounded at first like a contrived homework problem but then I thought he's probably trying to set up a dating websites and needs a process to prearrange the seating at a group meet&greet so don't go too harsh on him.