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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.

Review: Unique polyhedral dice from Maths Gear

Our good friends at Maths Gear have sent us a tube of “unique polyhedral dice” to review. The description on mathsgear.co.uk says they’re “made from polyhedra you don’t normally see in the dice world”. My first thought was that we should test they’re fair by getting David to throw them a few thousand times but — while David was up for it — I’d have to keep score, which didn’t sound fun.

So instead we thought of some criteria we can judge the dice on, and sat down with a teeny tiny video camera. Here’s our review:

Integer Sequence Review – Sloane’s birthday edition!

The Online Encyclopedia of Integer Sequences contains over 200,000 sequences. It contains classics, curios, thousands of derivatives entered purely for completeness’s sake, short sequences whose completion would be a huge mathematical achievement, and some entries which are just downright silly.

For a lark, David and I have decided to review some of the Encyclopedia’s sequences. We’re rating sequences on four axes: Novelty, Aesthetics, Explicability and Completeness.

CP: It’s Neil Sloane’s 75th birthday today! As a special birthday gift to him, we’re going to review some integer sequences.

DC: His birthday is 10/10, that’s pretty cool.

CP: <some quick oeis> there’s a sequence with his birthdate in it! A214742 contains 10,10,39.

DC: We can’t review that. It’s terrible.

CP: I put it to you that you have just reviewed it.

DC: Shut up.

CP: Anyway, I’ve got some birthday sequences to look at.

DC: About cake?

CP: No.

A050255
Diaconis-Mosteller approximation to the Birthday problem function.

1, 23, 88, 187, 313, 459, 622, 797, 983, 1179, 1382, 1592, 1809, 2031, 2257, 2489, 2724, 2963, 3205, 3450, 3698, 3949, 4203, 4459, 4717, 4977, 5239, 5503, 5768, 6036, 6305, 6575, 6847, 7121, 7395, 7671, 7948, 8227, 8506, 8787, 9068, 9351

CP and Cushing take the National Numeracy Challenge

banner-with-cp-and-cushing

Cushing was injured in a serious maths accident recently (he fell out of the bath) so I wanted to assess the damage to his number-wrangling faculties.

Fortunately, there’s the National Numeracy Challenge, which begins with a test to pinpoint your weak areas. National Numeracy is a charity that wants every adult in the UK to “reach a level of numeracy skills that allow them to meet their full potential.” Well, if there’s one thing we’ve got, it’s bags of potential.

Play

Integer sequence review: A193430

The Online Encyclopedia of Integer Sequences contains over 200,000 sequences. It contains classics, curios, thousands of derivatives entered purely for completeness’s sake, short sequences whose completion would be a huge mathematical achievement, and some entries which are just downright silly.

For a lark, David and I have decided to review some of the Encyclopedia’s sequences. We’re rating sequences on four axes: NoveltyAestheticsExplicability and Completeness.

This is the triumphant return of the integer sequence reviews!

A193430
Primes p such that p+1 is in A055462.

23, 6911, 5944066965503999, ...