downloading primes?

[wblipp]

Originally Posted by mnh001

If I'm trying to factor HP49(119) (which has 2 small factors 73 and 16249 plus a C251) I'm pretty sure the smallest factor of the c251 has quite a few digits.

Playing around with ideas like this is good way to get familiar with the various sources available and comfortable with using them. I suggest that in parallel you should also learn how to do heuristic estimates of the effectiveness of various ideas that you generate. For example, you could estimate the probability the C251 has a factor between 30 and 50 digits (or whatever bounds seem interesting), the number of such primes, the fraction of these primes that are in factordb, the time needed to test each - from which you could generate a probability of success and an expected run time. If you don't know how to estimate some of these steps, ask - people here are willing to help.

[mnh001]

Those are good ideas. Without even going that far I'm pretty sure the chances are slim of a success.
But I figured the time spent doing my approach would be minimal so there would little lost in trying.
Plus if it did work out for some number that gain would be huge. And the db covers such a wide range
of #'s of digits in those primes that it's way more than I could ever create myself. And as you say I'd learn
new things along the way. Thanks.

[xilman]

Originally Posted by mnh001

Those are good ideas. Without even going that far I'm pretty sure the chances are slim of a success.

A much more accurate substitution for "slim" is "somewhere between nil and negligible" but you should follow the suggestion and work out a numerical value, even if only to the nearest order of magnitude or two. You will learn something valuable if you do.

[Xyzzy]

Originally Posted by xilman

…"somewhere between nil and negligible"…