How to search the internet for strings that consist mostly of math notation? Is there a trick to search the internet for math notation?  For example what if I want to search the internet for "X / ~" ?  The default google search is useless for this and for similar searches where most of the search characters are not letters or numbers.  Google code search allows this kind of search within source code, but this service will shut down in a few months and anyway it searches only source code not math.
 A: See my side-project, it is developing its indices currently.
http://approach0.xyz
I will publish its first release when the entire math StackExchange is indexed.
Also, I am hoping someone interested can join and form a community to push this project forward, this is the reason I am posting here, even if this project is not fully ready for public using.
EDIT:
If you are interested in this project or have any amazing idea to help it improve, please follow this twitter account: https://twitter.com/approach0
, mention #approach0 to send feedbacks/questions. Approach0 will post updates on twitter too.
A: I recommend using symbolhound.com. I recently found this site, it will do a search for specific symbols, and is good for programming. May be good for math, just searched '4x^2' and it worked fine.
A: You can search for mathematical formulas and symbols using searchOnMath.
A: A few years ago we developed the search engine SearchOnMath, in order to search for mathematical formulas. Recently our tool has indexed both: Mathematics and MathOverflow.
Currently, SearchOnMath is the mathematical search engine with the largest number of indexed sites (including Wikipedia, Wolfram MathWorld, among others ...).
EDIT:
We released on September 2021 a Beta version for arXiv, available at searchonmath.com/arxiv.
Since March 2022 some results may be available only for subscribers. If you like SearchOnMath, please consider subscribing. This will help us on paying for our servers.
