Category Archives: primes

Prime Time in Haskell

Posted on January 6, 2011 by

In a recent blog post, Patrick Vennebush of Math Jokes 4 Mathy Folks noted that 2011 can be expressed as a sum of consecutive prime numbers, and challenged his readers to work out how. He also posed a couple further … Continue reading →

Posted in arithmetic, number theory, primes, programming | Tagged , , , | 8 Comments

Book Review: The Mystery of the Prime Numbers

Posted on November 7, 2010 by

Several months ago, Matthew Watkins sent me a review copy of his new book, Secrets of Creation Volume One: The Mystery of the Prime Numbers. It’s taken me a while to get around to reviewing it, but not for lack … Continue reading →

Posted in books, number theory, primes, review | Tagged , , , | 3 Comments

MMM #33: Super divisible

Posted on May 25, 2009 by

This week’s Monday Math Madness is up at Wild About Math!. Looks like a fairly accessible problem this week: What’s the prime factorization of the smallest whole number that is divisible by all integers from 1 up to and including … Continue reading →

Posted in challenges, links, number theory, primes | Tagged , ,

More on repetend lengths

Posted on January 27, 2009 by

In a previous post, I noted that the length of the repetend (repeating portion of the decimal expansion) of a fraction with prime denominator p is at most p-1, and in fact divides p-1. I also said: In fact, there’s … Continue reading →

Posted in group theory, number theory, pattern, primes | Tagged , , , , | 6 Comments

Two Very Large primes

Posted on September 17, 2008 by

As promised, I can now reveal the identity of the two newly discovered Mersenne primes. The smaller of the two, discovered on September 6 by Hans-Michael Elvenich in Langenfeld, Germany, is an 11,185,272-digit number which you can download here. The … Continue reading →

Posted in computation, famous numbers, links, primes | Tagged , , , | 3 Comments

New Mersenne primes!

Posted on September 15, 2008 by

The Great Internet Mersenne Prime Search just announced not one, but two new Mersenne primes! You might also recall the last time they announced a new prime, in September 2006, so these new primes were found almost exactly two years … Continue reading →

Posted in computation, famous numbers, links, primes | Tagged , , , , | 1 Comment

Perfect numbers, part III

Posted on November 27, 2007 by

This is the last in a series of posts about perfect numbers. A quick recap of the series so far: in part I, I defined perfect numbers as positive integers n for which , where denotes the sum of the … Continue reading →

Posted in algebra, number theory, open problems, primes, solutions | 11 Comments

Prime Shooter!

Posted on August 15, 2007 by

Today I came across this nifty Space Invaders-like game — except instead of shooting bullets at UFOs, you shoot prime factors at integers. For example, if the number 66 is falling towards you, you need to shoot it with 2, … Continue reading →

Posted in games, primes | 2 Comments

Open problems: Twin prime conjecture

Posted on April 10, 2007 by

Oops, so much for posting once a week! My excuse is that I’ve been hard at work on my book. Well, nothing to do but get right back at it. I promise* I will be better** about posting regularly*** from … Continue reading →

Posted in challenges, famous numbers, infinity, primes | 3 Comments

New bookshelf entry: The Book of Numbers

Posted on September 20, 2006 by

After seeing John H. Conway and Richard Guy‘s The Book of Numbers cited in yet another interesting article/book/whatever, I finally decided that I clearly had to read it. (It seems to get cited a lot in certain circles.) I wasn’t … Continue reading →

Posted in books, famous numbers, geometry, golden ratio, infinity, links, primes | 3 Comments