
UCLA group discovers 13-million-digit prime number - gibsonf1
http://www.sfgate.com/cgi-bin/article.cgi?f=/n/a/2008/09/27/state/n043052D04.DTL&tsp=1
======
iamwil
"Mersenne primes — named for their discoverer, 17th century French
mathematician Marin Mersenne — are expressed as 2P-1, or two to the power of
"P" minus one. P is itself a prime number. For the new prime, P is
43,112,609."

I think the last sentence is a mistake. If Mersenne primes are expressed as
2^P - 1, then the Mersenne prime is 2^43,112,609 - 1. as it's bigger than P.

~~~
antiform
The textual definition of everything is correct. There's just an error in the
formatting of 2^p - 1.

A Mersenne prime is a prime of the form 2^n - 1 for some n. The new biggest
Mersenne prime is 2^(43,112,609) - 1. An interesting coincidence is that the
power itself, 43,112,609, is also prime.

The definition given by the improper formatting of numbers in the article: (2
* 43,112,609) - 1 = 86225217 = 3 * 13 * 2210903 and so is not prime.

~~~
iamwil
2^n - 1 is the Mersenne prime, not the exponent, right? (Even though the
exponent is always prime).

So therefore, the new prime should be 2^43,112,609 - 1, and not just
43,112,609

