
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
Define an "equal sum sequence": In a sequence, if the sum of every term and its subsequent term is the same constant, then this sequence is called an equal sum sequence, and the constant is called the common sum. Given that the sequence $\{a_n\}$ is an equal sum sequence, with $a_1 = 2$ and the common sum is 5, the value of $a_{18}$ is ______.

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