
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
The sequence $\{{a_n}\}$ has initial terms ${a_1 = -7, a_2 = 5}$, and satisfies the recurrence relation ${a_{n+2} = a_n + 2}$ for all positive integers $n$. Find the sum $S_{18}$ of the first 18 terms of the sequence.

Present the answer in LaTex format: \boxed{Your answer}
user