Use set notation to list all the elements of the set. \[ \{15,18,21, \ldots, 36\} \]

Step 1 ：Identify the start, end, and step of the set. The start is 15, the end is 36, and the step is 3.

Step 2 ：Generate all the elements of the set using the arithmetic sequence formula. The elements are 15, 18, 21, 24, 27, 30, 33, 36.

Step 3 ：The elements of the set are \(\boxed{\{15, 18, 21, 24, 27, 30, 33, 36\}}\).