Alternating Permutation

How many permutation of the set $\{1, 2, 3, ..., 18\}$ is an alternating permutation with number $9$ as its first element?

Note that permutation $(9, 10, 8, 11, 7, 12, 6, 13, 5, 14, 4, 15, 3, 16, 2, 17, 1, 18)$ is an alternating permutation but $(9, 8, 18, 7, 17, 6, 16, 5, 15, 4, 14, 3, 13, 2, 12, 1, 11, 10)$ is not.

Write only the first $3$ digits of the answer!