# Primeness of Sevens

Since this month is devoted to the ins and outs of seven-ness, I thought a few facts would be appropriate.

So, here from Wikipedia, are some of the features of this prime number, which serve to prove that mathematics is a language of alien thought about real correspondences between imaginary concepts (All numbers, including seven, are imaginary. Try to find one.)

“Seven, the fourth prime number, is not only a Mersenne prime (since 23 − 1 = 7) but also a double Mersenne prime since the exponent, 3, is itself a Mersenne prime. It is also a Newman–Shanks–Williams prime, a Woodall prime, a factorial prime, a lucky prime, a happy number (happy prime), a safe prime (the only Mersenne safe prime) and the fourth Heegner number.”

“A safe prime is a prime number of the form 2p + 1, where p is also a prime. (Conversely, the prime p is a Sophie Germain prime.) This is considered important in cryptography: for instance, the ANSI X9.31 standard mandates that strong primes (not safe primes) be used for RSA moduli. I guess that strong primes are the dangerous ones.”

“In number theory, a lucky number is a natural number in a set which is generated by a ‘sieve’ similar to the Sieve of Eratosthenes that generates the primes.”

“A happy number is defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers, while those that do not end in 1 are unhappy numbers (or sad numbers).”

“In number theory, a Woodall number (Wn) is any natural number of the form
Wn = n × 2n − 1 for some natural number n. The first few Woodall numbers are:
1, 7, 23, 63, 159… Why that is a good thing is known only to Woodall.”

At this point, I lost the ability to parse the sentences as English. They were written primarily in math concepts, and I don’t know the language.

The one kind of math I can easily understand is that there are more ways to roll a seven with two cube dice than any other number, which makes me wonder even more why it’s so lucky to roll one.

This entry was posted in Babbling, Sevens, Ultimate Blog Challenge. Bookmark the permalink.