9. If a sequence of numbers, except for the first and last numbers, each number is equal to the sum of the two adjacent numbers, it is called a sequence with oscillatory property, for example $2,3,1,-2,-3, \cdots \cdots$. It is known that in the following sequence, each * represents a number and satisfies the oscillatory property.
$$
1, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, 1,
$$

Then the sum of the 18 numbers represented by * is $\qquad$ .
Answer: 0