Answer 1

Because you started with -1 (81) that mean from the last num and you ended with 1 if you count from the last 1 means the last number (81) you started the number where you end that's why it's empty list
You should use print(squares[1:-1])
You will get from 1 to 64
Or if you want different result please let me know.

Answer 2

In case you want to get values from last index(-1) to 1 ,then you will have to add negative step
squares[-1:1-1]