This is looking for a pattern. The first time is a/2, which is the first square of 2.

The second a/4, that is, the quadratic of 2, a and so on, is this law.

Therefore, the 20th13rd degree is a of 2 to the 20th13rd power.

But they asked something else.

So the answer is a-a/2 power of 20 13.

You got it?

The answer you adopted is wrong, don't you see?