> The sieve of Eratosthenes comes alive in this animation, which shows multiples of each prime loping along the number line.<p>A more accurate depiction would not have a bunch of prime curves starting from 0, but would have each one sprouting from its prime just when that prime is passed over by all existing prime curves.
If you just make up a number claim it’s prime and nobody disputes it, it’s prime apparently. I don’t think it’s really possible to have a very large prime number, because unless someone has tried every factor it’s really not prime yet, honestly that explains a lot about the elusiveness of the concept.