Finally, I found the following argument expansion can work.

 Y= [Y[0],*Y[1:n//2]*2]

Since we can have

 >>>a, *b, c = [1, 2, 3, 4, 5] to 
 >>>b
 >>>[2, 3, 4]

Also if

>>>a = [*'PYTHON']
>>>a
>>>['P', 'Y', 'T', 'H', 'O', 'N']