[codepie]

I have been using Zim[0] for quite few years now. With various plugins, it allows me to write LaTeX equations, formatted code, tables etc. Overall it has been really good, but I feel the only thing missing is the support for mobile devices.

[0]: http://zim-wiki.org/

[NIckGeek]

This notepad app does support LaTeX equations (instructions are in the help notepad). Sadly it might be an issue on mobile for you too.

MicroPad _works_ on mobile, but not very nicely. That is a key thing I want to improve though.