Other operators, equations?

[tautologico]

Are there plans to include other operators, like summations (\Sigma), products (\Pi), integrals and so on? What about equations and systems of equations? I'm interested in experimenting with sums and recurrence relations, so it would be good to have the basics available in the library.

I can send a PR with the operators at least, but I wanted to ask first if this is in scope, and where should I add them.

[FoggyFinder]

In my opinion it is a good idea. Only need to consider how it will look.