Thread: Prime numbers question

I have this table listing the first 500 prime numbers. Some numbers are printed in blue (mostly lower numbers) while the rest are printed in red.
I have not been able to find what makes these two groups different. Could someone please explain this? Thanks.

Originally Posted by BERMES39

I have this table listing the first 500 prime numbers. Some numbers are printed in blue (mostly lower numbers) while the rest are printed in red. I have not been able to find what makes these two groups different. Could someone please explain this? Thanks.

Perhaps if you supplied more of the context in which this table appears someone could give a very good guess if not an outright explication.

I have stared at this for about a half an hour and cannot figure any rule out that separates the blues from the reds. I've looked up all sorts of different types of primes and nothing seems to work. Probably because I just haven't looked hard enough.