I encountered a website that had a large number of possible closed forms per a user number entry. It is not WA. I cannot locate it now. I had it saved before having to reinstall my browser. Anyone know of the site?
It is not OEIS. The site collects just single number entries, not sequences.
If I am curious if there's a closed form for a [truncated decimal representation of a] number such as 0.124578098472362 I would simply enter it and I'd see a list of possible closed forms for the number.
As jca recognized in a comment, this is the Inverse Symbolic Calculator.
Back in 2013, this site had a community ad for ISC, but nobody proposed such an ad for 2014 or 2015.