
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
In the sequence ${a_n}$, $a_1=2$ and $a_2=1$. The formula $\frac {2}{a_{n}} = \frac {1}{a_{n+1}} + \frac {1}{a_{n-1}}$ ($n\geq2$) holds true. Determine the general term formula for the sequence ${a_n}$, denoted as $a_n=_\_$.

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