ok, my bad then. Didn't know it worked different in python2 and python3. Thx for explanation

In Python 2.7, the / operator uses integer division and returns an int if both operands are int.

This passed the kata so, maybe it works after all? :)

https://stackoverflow.com/questions/21316968/division-in-python-2-7-and-3-3

this doesn't work because of n / 2 part instead of n // 2. How is it possible that this is top ranked answear?

The best practice for iterating over a sequence when both the index and the value are required is to use the builtin enumerate() function: https://docs.python.org/2/library/functions.html#enumerate