James Grime has “Numberphile”, a series of videos about various numbers and how they relate to more serious bits of maths. He goes outside with a big piece of paper, a marker, and a cameraman, and films himself talking and writing on the paper. (But you don’t have to watch him write! Thanks to the magic of film editing, the numbers appear one by one.) In this one on 220 and 284, “amicable numbers” — the factors of 220 add up to 284, and vice versa. Over at Maths Gear they’re selling pairs of keyrings with these numbers inscribed on them.

James points out that although the (220, 284) pair was known to the ancients, and Euler had found thirty pairs by 1747, it wasn’t until 1866 that B. Nicolò I. Paganini (as far as I know, no relation to the violinist) discovered the pair (1184, 1210). I’m a little surprised by this; you hear the story of great feats of calculation in that era, how did this one slip by? It reminds me of the fact that supposedly people thought was prime when 2047 is trivial to factor by trial division. At least, if you have Arabic numerals…

The whole Numberphile channel is here (currently 19 videos, a couple hours in total). Some of my favorites are:

• 3/4 and Kleiber’s law. The metabolic rate of an animal goes up at the 3/4 power of its mass, perhaps due to metabolic scaling;
• 17 is the minimal number of clues needed to solve a sudoku. On a related note, Jason Rosenhouse and Laura Taalman have a book, Taking Sudoku Seriously
• the initial video on the >number 11, released, somewhat inevitably, on 11/11/11. (If you’re in the UK, that’s 11/11/11.)

Okay, not really. I don’t know German. I took “German for reading knowledge” one summer in grad school and I’ve forgotten almost all of it.

But I miss mathblogging. I worked at it for a few years and then I started to become self-conscious about my mostly dormant blog at blogspot. Who uses blogspot any more?  And blogspot seems difficult to use for “serious” blogging — typing mathematics was difficult.  But here on wordpress, it’s easy. Did you know that ? And that ? Really, they do.

My old math blog was called God Plays Dice. It started out as a project to procrastinate in the summer after I passed my oral exams; as you can see from the posting history there it had a couple good years but then I lost interest. This blog, too, is called God Plays Dice. The reason for the new subdomain name is because godplaysdice.wordpress.com is taken.

One major difference, I hope, is that while my old blog was a blog about mathematics, this will be the blog of a mathematician. Or, these days, perhaps a statistician — I’m teaching statistics at Berkeley and spending a lot of time around people who think about data has likely influenced what goes on in my head. Four and a half years ago I was looking inward, looking towards research and my dissertation; now I’m on the other side of graduation, looking towards what the rest of life will bring.  And as Twitter has taught us, links without lots of accompanying commentary are worthwhile; that’s something I shied away from in the old days, but I’m hoping to change that this time around.

Here’s to a fresh start, on the second day of the second week of the second month of the second year of the second decade of… um… the second millennium, if you start counting millennia at zero?