[R] statistical significance

[João Fadista]

Dear all, 
 
I would like some advise about which package and functions should I use for my problem in hands.
Let say I have small sequences that are mapped into a long sequence. And some of these small sequences are more mapped into some regions than others. 
 
So what I want is to give some statistical significance of that regions that are "crowded" with the small sequences for me to make conclusions. Therefore, I would like to have a statistical significance test saying that "the region A is probably more dense in the small sequences tha region B". 
 
Thanks in advance
 
Best regards,
João Fadista