>>11133379You have to consider every sequence, since gaining a new digit is always going to get you a bigger number.
It's just that most of those sequences terminate really fast. The 1-digit primes are 2, 3, 5, 7, and half of those have no primes ending in them, just as the most trivial example. By the time you get up to more than 10 digits, I doubt there's many left.
