For quite some time now (at least a year), whenever I tried to use Plouffe's inverter, the request timed out, but there's no indication either on the site itself or on the Web that it's out of service or having problems. Does anyone know whether it's still online? Have I just been extremely unlucky?

Also, if it really is offline or practically unusable, do you know of any alternatives? I know OEIS, but that's for integer sequences, and its use for decimal representations of real numbers feels a bit unnatural (though it has quite a few sequences of that kind).

  • $\begingroup$ Wolfram Alpha... $\endgroup$ – Hans Lundmark Oct 24 '12 at 19:14
  • $\begingroup$ @Hans: Cool, I didn't know it does that :-) $\endgroup$ – joriki Oct 24 '12 at 20:59
  • $\begingroup$ About 2 weeks ago, seeing such matters, I succeeded to find a substitute on the Internet. It worked fine. Now I'm trying to track it down again -- and I can't! I did not remember that working URL, because I thought the flaw at the original site was temporary. If I find the working software again, I'll share the URL with you. $\endgroup$ – user51003 Nov 28 '12 at 10:52
  • $\begingroup$ Heh. I guess you've cleared your cache since then? $\endgroup$ – Simon Hayward Nov 28 '12 at 11:14
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    $\begingroup$ Additional Resources : RIES, Wolfram Alpha, the 'old' ISC. $\endgroup$ – Raymond Manzoni Apr 19 '16 at 9:13

Try one of these:

  • $\begingroup$ Great, thanks, exactly what I was looking for! $\endgroup$ – joriki Nov 28 '12 at 11:34
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    $\begingroup$ From the ISC+ site: The lookup tables include a substantial data set compiled by S. Plouffe both before and during his period as an employee at CECM. So it seems to be the legitimate successor to Plouffe's inverter. $\endgroup$ – Christian Clason Nov 28 '12 at 13:07

I am told that the server it used to run on at UQAM doesn't exist anymore, and there are no plans to revive it there.

Edited to add: in response to a suggestion from me, the former Plouffe's Inverter site now admits that the Inverter no longer exists, and redirects users to the Inverse Symbolic Calculator Plus mentioned in the answer above.


It seems that all the referenced websites are down, at least for the moment. However, I just noticed the following on Simon Plouffe's website:

2016 : Portable version of the Plouffe Inverter : Version portable de l'Inverseur de Plouffe. 3 billion entries at 32 digits precision.

This portable version can be accessed here.

  • $\begingroup$ Thanks for this answer. But this seems to be just a set of directories with lots of text files with numbers in them. So I'd say it's not really a portable version of the inverter, just a data set that you can use to build your own inverter. $\endgroup$ – joriki Aug 29 '16 at 6:25
  • $\begingroup$ @joriki Sure, but notice that the data is sorted by the associated real number, so it shouldn't be hard to look for expressions if you only need to make one or two queries. But anyway, it seems like isc+ is up! $\endgroup$ – Bjarki Ágúst Guðmundsson Sep 13 '16 at 0:19

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