Comment by Sanddancer

Using any sort of device -- be it a phone app that keeps track of random number seeds, or an old school blackjack computer that works via foot taps -- has been illegal for a long while. It makes things no longer a game of chance. Much like how a casino's not allowed to use weighted dice, you're not allowed to use your own probability shifters. Now, if the people that are being discussed were doing this in their head, it wouldn't be illegal. The casinos would be angry at these people, call them mean names, and probably blacklist them, but it wouldn't be a crime. It's only once you add that device to make it something other than a game of chance does it become a crime.