
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
Let ${S_n}$ be the sum of the first $n$ terms of an arithmetic sequence ${{a_n}}$ with ${a_1}=1$. Given that $\frac{S_{2017}}{2017} - \frac{S_{2015}}{2015} = 1$, the sum of the first $2017$ terms of the sequence ${\left\lbrace \frac{1}{{{S_n}}} \right\rbrace}$ is (   ).

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