Python3 RE issue with '\n'

Question

I'm trying to do a simple regular expression in Python3 that just provides me the Twitter id.

Why does the following not work?

import re
s="twitter.com/atechnofou\\nInstagram:"
all_matches = re.findall("twitter\.com/[^?\\\"\'>&\*\n\r\ <]+", s)

It returns: ['twitter.com/atechnofou\nInstagram:']

But I'd like it to return ['twitter.com/atechnofou']

---

If I change my re.findall to this, it works, but why?

all_matches = re.findall("twitter\.com/[^?\"\'>&\*\n\r\\\ <]+", s)

All I've done is moved the \\ from the beginning of the [] block to closer to the end.