That is not a requirement though. Neither by description, nor by test.
Also insertion-order preservation in dictionaries depends on the python version.

literally a recursive directory creation.
Had to do this :)

The examples in the description don't reflect the case insensitivity.

As a suggestion remove one lowercase b in
"aabbcdeB" -> 2 # 'a' and 'b'

I ran into this as I primarily looked in the examples ;)

Otherwise a nice one imo

only draw back in this version is the inefficient ammount of recursions.
e.g. if n=1000 you would otherwise run down to n<1 which is not necessary (easy to solve ;))

besides that you might as well break if n == 2 as we know this to be true. No need to to another call to isPowerOfTwo(1) ;)

os.system is dangerous. IIRC os.system will spawn a shell, so you're vulnurable to code injection.