Integer Sequence Reviews: A075771, A032799, A002717

It’s been almost two years since I last sat down with my friend David Cushing and did what God put us on this Earth to do: review integer sequences.

This week I lured David into my office with promises of tasty food and showed him some sequences I’d found. Thanks to (and also in spite of) my Windows 10 laptop, the whole thing was recorded for your enjoyment. Here it is:

I can only apologise for the terrible quality of the video – I was only planning on using it as a reminder when I did a write-up, but once we’d finished I decided to just upload it to YouTube and be done with it.

Puzzlebomb – July 2016

Puzzlebomb Logo

Puzzlebomb is a monthly puzzle compendium. Issue 55 of Puzzlebomb, for July 2016, can be found here:

Puzzlebomb – Issue 55 – July 2016 (printer-friendly version)

There’s also an online electronic version of the puzzle in this issue.

The solutions to Issue 55 can be found here:

Puzzlebomb – Issue 55 – Solutions – July 2016 (printer-friendly version)

Previous issues of Puzzlebomb, and their solutions, can be found at Puzzlebomb.co.uk.

Exam timing

When I have been involved with running exams (I wasn’t, really, this year), special care seems to be made to spread these out so that where possible students don’t get exams bunched together. Still, I’ve heard students complain “we only have one day off between the Monday and Wednesday exams, that isn’t enough time to revise for the second topic”. I have a lot of sympathy for this; assessing a module (or proportion thereof) by how you perform in a one-, two- or three-hour window is quite a problematic arrangement, and if you haven’t had sufficient time to get up to speed on the topic, even more so. But I have had in mind that, essentially, “when I were a lad, we had it much worse”. Clearing out some boxes to move house, I found exam timetables from five of the six semesters I spent as an undergraduate, so now I can confirm or refute my feeling on this, in the latest of my series of posts that are surely only of interest to me.

Binary/Nail Varnish Puzzle – solution

Previously, we posted about Katie’s Binary Nail varnish tutorial video, and how you can use glitter (1) and no glitter (0) to encode binary messages in your nail varnish. We also posted an accompanying puzzle, stated as:

Suppose I want to paint my nails on one hand differently every day for a month – so I need to use all 31 combinations involving glitter. Assuming that a nail painted with plain varnish can have glitter added, but a nail with glitter needs to be nail-varnish-removed before it can become a plain nail again, what order do I apply the different combinations so that you minimise the amount of nail varnish remover I’ll need to use?

Here’s our take on the solution.

New MathJax accessibility extensions provide collapsible expressions and maths-to-speech

MathJax, the web library that provides LaTeX-quality mathematical typesetting, has received a a new set of tools to improve accessibility of mathematical notation. The new MathJax Accessibility Extensions add on-the-fly speech rendering of notation, and a tool to explore expressions through intelligent collapsing and expanding of sub-expressions.