1. 24 21 19 18 15 13 _ _ 7

The pattern appears to be the difference between consecutive numbers.
24 - 21 = 3, 21 - 19 = 2, 19 - 18 = 1, 18 - 15 = 3, 15 - 13 = 2.
The differences are not consistent.
Let's look at the last numbers: 7.
It is possible that the sequence is related to squares or cubes, or a more complex pattern.
Without further context or a clear pattern, it is difficult to definitively solve this. However, if we assume a repeating pattern of differences or a specific mathematical operation, we might find a solution.
Given the limited information and potential for multiple interpretations, a definitive answer cannot be provided.
The question is incomplete or requires external knowledge.