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… Read more »

# 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 300,000th 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… Read more »

# 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.

# LMS Meeting in honour of Maryam Mirzakhani

The London Mathematical Society are organising an event later this month in honour of the late Fields Medalist Maryam Mirzakhani. It's at the University of Warwick on 22nd March, and will include talks outlining some of Mirzakhani's work, followed by a drinks reception and dinner. The event is part of a larger EPSRC symposium on Teichmüller dynamics.

# 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.

# πkm Running Challenge: 7-day update

Katie’s running πkm per day for charity, every day in March. Seven days in, here’s how she’s getting on.

# Carnival of Mathematics 155

The next issue of the Carnival of Mathematics, rounding up blog posts from the month of February, and compiled by Ben, is now online at Math Off The Grid.

The Carnival rounds up maths blog posts from all over the internet, including some from our own Aperiodical. See our Carnival of Mathematics page for more information.