If you’ve worked with or used any sequences of integers lately (and let’s face it, you have) you might have looked them up in the OEIS. I’ve used it twice today, and it’s still before 9.30am. As you may have gathered from our extensive banging on about it, we’re huge fans of the Online Encyclopedia of Integer Sequences.

If you have visited their site recently, you might have noticed an extra paragraph of red text near the top – yes, they’re doing a Wikipedia, and asking for their users (which is realistically everyone) to donate so they can keep going. It’s a hugely worthy cause, and here at the Aperiodical, we think it’s worth supporting. The OEIS is owned and maintained by The OEIS Foundation Inc., a nonprofit company.

Head over to the OEIS for lists of integers with various properties, and to find out more.

### More information

The Online Encyclopedia of Integer Sequences.

How to donate to the OEIS Foundation.

Hi Katie! Thanks for mentioning our annual appeal. Much appreciated.

(I run the OEIS, as I have been doing for 49 years.)

One of the pleasures of running the OEIS is seeing the totally new sequences that get submitted every day. I could mention many examples, but a recent favorite is A228407, an invention of Eric Angelini in Brussels.

But be careful, it could cause loss of sleep.