Yet another question that seems highly likely to be homework, but at the same time, perhaps not. At the same time, you need to remember the list will be a long one if the number of bits is large. However, then I look at your other questions, and it seems you have asked some fairly simple questions, one of which is quite close. That makes it far more likely this is homework.
- Start with a list of all primes less than 2^(n-1).
- Form the product of all pairs of those primes.
- Delete the products that have less than n bits, or more than n bits.
Surely you can handle step 1.
As for step 2, just read the responses to one of the last questions you asked.
Finally, how can you compute the number of bits in a number? What would log2 tell you?
If you want a less memory intensive solution, surely you can do exactly the same thing using a loop, computing products of pairs of primes, saving those that have exactly n bits. Again, log2 would be your friend here, since it will allow you to efficiently know which primes to use in that product. A careful implementation would even allow you to do this efficiently, by computing the log2 of every prime in the initial list.
Finally, If you convinced me this is not homework by explaining why you want this list, AND you showed a reasonably serious effort you made, I would offer more help. I'll bet it is homework though.
