can anybody please
Let n = 2^31 x 3^19. How many positive divisors of n^2 are less than n but
do not divide n?
p is prime and .
Then, from here, we subtract 1 because the highest factor is .
Just read the factors can't divide n.
We know that .
Therefore, we must subtract
31 are the number of multiple of 2s, 19 are the multiple of 3s, and 19 are the multiples of 6.
However, this includes some overlap. Your job is to figure out how many to add back in.
Suppose . Then there exist some and such that . Moreover, iff or . Next, and . Therefore, if and , then either (1) or (2) . Note that (1) and (2) are mutually exclusive. Conversely, for each and each , and . Similarly, for each and each , and .
Therefore, the answer is . According to my brute-force calculations, this is 589.
Maybe someone will figure out a more elegant solution.