Hexaflexagons are great.
If you haven’t seen one before, you’re about to have a lovely time.
If you have seen them before, the reason I’m writing about them is that I’ve made a webpage that helps you create a template for a hexaflexagon with your choice of picture on each of the three faces.
A couple of days ago, a question occurred to me:
What’s the furthest I’ve ever been from anyone else?
In December I organised a series of online public maths talks called What Can Mathematicians Do?
The recordings of the talks are now online, free for anyone to watch. You could go to the official page I put up on Newcastle University’s website, or you could just watch them here!
This week and last I hosted a series of public maths talks featuring disabled presenters. I’ll post about how that went later, but for now I just want to share this clip of me filling time spreading Christmas joy.
This is a party trick that Katie Steckles showed me: you can fold a piece of paper and then make a single cut to produce a five-pointed star. I showed how to do it by following the instructions I’d been told, and then recreated the steps just starting from the insight that when you make the cut, all the edges of the shape need to be on top of each other.
Maybe you’ll show someone else how to do it during the Christmas holiday?
This doesn’t only work for stars: there’s a theorem that you can make any polygon by folding and a single cut. Erik Demaine has made a really good page about the theorem, with some examples to print out and links to research papers. Katie can cut out any letter of the alphabet on demand, which is impressive to witness!
It’s nine years since the first integer sequence review, and six years since the last one. We’ve grown as people, and in CLP’s case, grown people. The world has changed, but our love for the Online Encyclopedia of Integer Sequences hasn’t.
Smallest permutation of the natural numbers with $a(3k-2) + a(3k-1) = a(3k)$, $k > 0$.
1, 2, 3, 4, 5, 9, 6, 7, 13, 8, 10, 18, 11, 12, 23, 14, 15, 29, 16, 17, 33, 19, 20, 39, 21, 22, 43, 24, 25, 49, 26, 27, 53, 28, 30, 58, 31, 32, 63, 34, 35, 69, 36, 37, 73, 38, 40, 78, 41, 42, 83, 44, 45, 89, 46, 47, 93, 48, 50, 98, 51, 52, 103, 54, 55, 109, 56, 57, 113, 59, 60
I’m organising a series of online public maths talks through my work, the School of Maths, Stats and Physics at Newcastle University.
The point is that talks will be delivered by disabled presenters. This came about because I and some other disabled people who do maths talks got tired of missing out on opportunities to do outreach because it involves travelling. Not every disability makes travelling harder, but we felt that there were enough people excluded by in-person events that it would be nice to put on a more accessible event.
My aim is for this to take place in December 2022, near to the International Day of People with Disabilities. Talks can be any mathy topic, or about your experience as a disabled mathematician.
I need speakers!
To give some idea of what I’m looking for, I’ll use myself as an example. I count myself disabled at least four ways: I’m colourblind, autistic, dyspraxic, and have Ehlers-Danlos syndrome.
I might talk about:
The sessions will be delivered over Zoom, with live captions written by humans and a BSL interpreter. (If you can recommend a BSL interpreter with experience of interpreting maths talks, please get in touch!)
We’ll be advertising the talks to the general public, both grown-ups and schools, so I’m not looking for talks about high-level maths or education research.
This is open to anyone around the world, but if you’re a long way from the UK bear in mind that we’ll schedule the sessions at a convenient time for a British audience.
If you’re interested in taking part, please email christian.perfect@ncl.ac.uk.
I’d like to have a list of presenters by the end of September, to leave plenty of time to arrange whatever needs to be arranged and to advertise the talks.
Here’s a game I’ve been trying to make for a while.
For a while I’ve had a hunch that there’s fun to be had in moving between numbers by using something related to the prime numbers.
Over the years I’ve tried out a few different ideas, but none of them ever worked out – they were either too easy, too hard, or just not interesting. This time, I think I’ve found something close enough to the sweet spot that I’m happy to publish it.
Prime Run is a game about adding and subtracting prime numbers. You start at a random number, with a random target. Your goal is to reach the target, by adding or removing any prime factor of your current number.