### That Makes It Invertible! (by The Three Directions)

Put a smile on your face this Friday morning. Here, straight out of Harvey Mudd College, are the Three Directions performing their new smash hit, That Makes It Invertible!

via MetaFilter

### Amazing Sierpinski Tetrahedron

In the wake of a flurry of tetrices being constructed in schools all over the country (see this post about fractal Christmas tree worksheets, and this post featuring photos of completed trees), we’ve also been sent a video of a school group constructing an ambitious and impressive fractal structure, using envelopes cleverly folded into tetrahedra. The video is below, and features (eventually) a level 5 Sierpinski Tetrahedron, made from 1024 envelopes!

Via teacher Tim Dolan on Twitter.

### Videos from MathsJam 2012

While we were at the big MathsJam conference a few weekends ago, we took the opportunity to point a camera in people’s faces and ask them to tell us something interesting. Because of the high quality of MathsJam attendees, this went better than it would in most other contexts.

Here’s a collection of clips we recorded while people were digesting both their dinners and the first day’s talks.

### Recreational Maths Seminar – Seven Staggering Sequences

Yesterday I hosted another recreational maths seminar on Google+. I had a lot of fun! We discussed the paper, Seven Staggering Sequences (PDF), by Neil Sloane. In the paper Sloane, the man behind the fantastic Online Encyclopedia of Integer Sequences, described seven of the sequences he found most especially interesting.

The Hangout was just under an hour and a half long, and we managed to get through five of the seven sequences. Some of them are really hard to understand!

### Recreational Maths Seminar – Picture-hanging puzzles

I hosted the first (proper) Aperiodical recreational maths seminar yesterday. We discussed the paper Picture-hanging puzzles, by Demaine et al. Click through to watch the YouTube recording of the session.

### A recreational maths seminar?

Would you be interested in taking part in a sort of online video-chat seminar about recreational maths? Then read on!

### The Calculus of Love, a short film

The Calculus of Love is a short film by writer/director Dan Clifton and starring Keith Allen. The film’s distributor got in touch with us last week to direct our attention toward the film, with the following synopsis:

Mathematics Professor AG Bowers is obsessed with solving the fabled 250 year old Goldbach Conjecture. When a series of mystery letters arrive hinting at a solution, Bowers believes his lifelong dream may at last be within reach.

After being shown at various film festivals, the film is now available to view online. I’ve embedded it below the fold, along with an interview with the film’s director, Dan Clifton.