
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
Analogous to arithmetic progression, an "equal sum sequence" is defined as: in a sequence, if the sum of each term and its subsequent term equals the same constant, then this sequence is called an equal sum sequence, and that constant is called the common sum. It is given that the sequence $\{a_n\}$ is an equal sum sequence with $a_1=2$ and the common sum is $5$. Find the sum of the first $2017$ terms, $S_{2017}=$ ______.

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