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Integer sequence review: A051200

By Christian Lawson-Perfect and David Cushing. Posted May 13, 2013

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’ll be rating sequences on four axes: Novelty, Aesthetics, Explicability and Completeness.

A051200
Except for initial term, primes of form “n 3’s followed by 1”.

3, 31, 331, 3331, 33331, 333331, 3333331, 33333331, 333333333333333331, 3333333333333333333333333333333333333331, 33333333333333333333333333333333333333333333333331, ...

Integer sequence review: A010727

By Christian Lawson-Perfect and David Cushing. Posted May 7, 2013

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’ll be rating sequences on four axes: Novelty, Aesthetics, Explicability and Completeness.

A010727
Constant sequence: the all 7’s sequence.

7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, ...

Integer sequence review: A225143

By Christian Lawson-Perfect and David Cushing. Posted May 4, 2013

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’ll be rating sequences on four axes: Novelty, Aesthetics, Explicability and Completeness.

A225143
Primes from merging of 10 successive digits in decimal expansion of $\zeta(2)$ or $\frac{\pi^2}{6}$.

9499012067, 4990120679, 3040043189, 1896233719, 2337190679, 9628724687, 2510068721, 8721400547, 9681155879, 5587948903, 7564558769, 9632356367, 3235636709, 3200805163, 4445184059, 3876314227, 2276587939, 1979084773, 9420451591, 9120818099, ...

All Squared, Number 4: How interesting!

By Christian Lawson-Perfect and Katie Steckles. Posted April 9, 2013

It’s a repeat booking for the Festival of the Spoken Nerd in number 4 (or 16 if you belong to Team All Squared) of our podcast. Standup mathematician Matt Parker joined us to talk about interesting coincidences.



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Recreational Maths Seminar – Seven Staggering Sequences

By Christian Lawson-Perfect. Posted December 3, 2012

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!

[youtube url=http://www.youtube.com/watch?v=MBvyaku9Omw]

Recreational Maths Seminar this Sunday at 7pm GMT

By Christian Lawson-Perfect. Posted November 27, 2012

There was no Recreational Maths Seminar last Sunday because I had a confluence of work, family stuff and overknackeredness from MathsJam the week before. The coming weekend should be considerably less busy, so let’s have our second seminar this Sunday, the second of December, at 7pm GMT. That’s 2pm EST (New York), 11am PST(California) and 6am EDT (Eastern Australia, on the 3rd of December).