Re: factor and large prime numbers

[Sami Kerola]

On 22 July 2013 16:01, Sami Kerola <address@hidden> wrote:
> I were curious how quickly factor will process prime numbers, and
> found something rather strange. For example these five can be computed
> quite quickly.
>
> time factor 10333147966386144929666651337523199999999
> time factor 371993326789901217467999448150835199999999
> time factor 13763753091226345046315979581580902399999999
> time factor 523022617466601111760007224100074291199999999
> time factor 20397882081197443358640281739902897356799999999

Opps. A silly mistake. Not only one of the above is prime.

time factor 523022617466601111760007224100074291199999999

But that hardly changes the strangeness...

> But much smaller numbers will take ages to give results (to be honest
> I gave up).
>
> time factor 8683317618811886495518194401279999999
> time factor 295232799039604140847618609643519999999
>
> Any idea what is going on?

...smaller primes can be a lot slower to factor than greater.

--
Sami Kerola
http://www.iki.fi/kerolasa/