
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, $a_{1}=1$, and the sequence $\{a_{n+1}-3a_{n}\}$ is a geometric sequence with first term $9$ and common ratio $3$.
(I) Find $a_{2}$, $a_{3}$;
(II) Find the sum of the first $n$ terms, $S_{n}$, of the sequence $\{\frac{a_{n}}{3^{n}}\}$.

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