The OEIS is amazing, I used to spend hours creating sequences using arbitrary algorithms and look it up to see if it has an alternate definition and what's the meaning and the history of this sequence.

Does it have an analogous for constants?

After some search I found the RIES (http://mrob.com/pub/ries/) and the ISC(http://isc.carma.newcastle.edu.au/index) which are amazing, and also I can use Wolfram Alpha to get a hint, but these resources are nothing like the OEIS, they aren't really like an Encyclopedia, they don't tell the history and the definition of the number, they just use clever algorithms to make 'inverse calculations' based on the given number.

Is there something more like to the OEIS?

  • 1
    $\begingroup$ You may in fact find many explanations about constants in OEIS by looking up the decimal expansion, e.g., oeis.org/… $\endgroup$ Feb 2, 2015 at 12:54
  • $\begingroup$ Yes, for example, try this search in the OEIS: 0.076923076923. Or this one: 0.6626069. $\endgroup$ Mar 6, 2015 at 5:16
  • $\begingroup$ Perhaps, using OEIS, if you get a name for your number, then the Internet can find out all bout it! $\endgroup$
    – GEdgar
    Jun 9, 2015 at 19:20

2 Answers 2


As pointed out in the comments, the OEIS is probably your best bet. It contains nearly 10,000 constant sequences, which you can look up by typing in their decimal expansion:

OEIS search for 3.14159

RIES is a good resource for numbers constructed as simple formulas. Plouffe has a private version of the ISC which is too large to be available online, but he's expressed willingness in the past to do lookups on demand. But neither of these resources have the same kind of encyclopedic focus as the OEIS.


I once chanced upon this book at the library: A Dictionary of Real Numbers.

It's a very interesting endeavour, to say the least. And maybe you'll find it similar to what you're looking for.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.