The Lucas-Lehmer test can determine if one of them is of interest. All even perfect numbers are the product of a power of 2 and a prime one; for examp
The Lucas-Lehmer test can determine if one of them is of interest. All even perfect numbers are the product of a power of 2 and a prime one; for example, 28 is "2 squared times 7" and 496 is "2 to the fourth times 31".  For ten points, what are these numbers named for a Minim friar which are of the form "2 to the nth minus one"?
The Lucas-Lehmer test can determine if one of them is of interest.
Mersenne numbers (reluctantly accept Mersenne primes)