I’ve made another one of my interactive online maths doodads. You should have a go at it right now. It doesn’t require any effort on your part, other than coming up with a positive integer.

# You're reading: Posts By Christian Lawson-Perfect

### Exactly how bad is the 13 times table?

Let’s recite the $13$ times table. Pay attention to the first digit of each number:

\begin{array}{l} \color{blue}13, \\ \color{blue}26, \\ \color{blue}39, \\ \color{blue}52 \end{array}

**What happened to $\color{blue}4$‽**

A while ago I was working through the $13$ times table for some boring reason, and I was in the kind of mood to find it really quite vexing that the first digits don’t go $1,2,3,4$. Furthermore, $400 \div 13 \approx 31$, so it takes a long time before you see a 4 at all, and that seemed *really* unfair.

### The OEIS now contains 300,000 integer sequences

The Online Encyclopedia of Integer Sequences just keeps on growing: at the end of last month it added its 300,000^{th} entry.

Especially round entry numbers are set aside for particularly nice sequences to mark the passing of major milestones in the encyclopedia’s size; this time, we have four nice sequences starting at A300000. These were sequences that were originally submitted with indexes in the high 200,000s but were bumped up to get the attention associated with passing this milestone.

### Proof by sedition

\[ n > 2 \]

An unexpected bit of controversy involving mathematical notation hit the internet last week, when China's government briefly blocked all Chinese internet users from viewing any page or message containing the letter *n*.

Apparently, those in charge of the Great Firewall feared that those who disapproved of Xi Jinping removing the two-term limit on his presidency of China would use the letter *n* to refer to the now-arbitrary number of terms for which he can remain in power.

There's some more context in a post by Victor Mair on Language Log, and in the Guardian.

### Faces of Women in Mathematics

This is nice for International Women's Day. Filmmaker Irina Linke and mathematician Eugénie Hunsicker have put together this montage of women in maths from all around the world.

### Stanisław Ulam biopic

There's going to be a biopic of physicist/mathematician Stanisław Ulam, titled *Adventures of a Mathematician*.

Hollywood seems to be working its way through 20th century mathematicians – off the top of my head, there have recently been biopics of John Nash, Alan Turing, Stephen Hawking and Srinivasa Ramanujan. What I want to know is, *when do we get Michael Sheen playing John Horton Conway?*

There's some information about *Adventures of a Mathematician*, starring Jakub Gierszal as Ulam, at ScreenDaily.

*via MathFeed on Twitter.*

### Are you more likely to be killed by a meteor or to win the lottery?

This tweet from the QI Elves popped up on my Twitter timeline:

The odds of being crushed by a meteor are considerably lower (i.e. more likely) than those of winning the jackpot on the National Lottery.

— Quite Interesting (@qikipedia) January 11, 2018

In the account’s usual citationless factoid style, the Elves state that you’re more likely to be crushed by a meteor than to win the jackpot on the lottery.

The replies to this tweet were mainly along the lines of this one from my internet acquaintance Chris Mingay:

Should we not be getting almost weekly stories of people being crushed by a meteor then ?

— Chris Mingay (@GhostMutt) January 11, 2018

Yeah, why don’t we hear about people being squished by interplanetary rocks all the time? I’d tune in to that!