There are quite a few of those scammy online auction sites that do "Unique bid auctions" -- same concept, just not restricted to prime numbers. Since there is

There are quite a few of those scammy online auction sites that do "Unique bid auctions" -- same concept, just not restricted to prime numbers. Since there is (possibly) a bit of skill involved, it makes it interesting from a legal perspective. http://en.wikipedia.org/wiki/Unique_bid_auction http://en.wikipedia.org/wiki/Unique_bid_auction