
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 arithmetic sequence $\{a_{n}\}$ with a non-zero common difference, $a_{2}=3$, and $a_{1}$, $a_{3}$, $a_{7}$ form a geometric sequence.
(1) Find the general term formula for the sequence $\{a_{n}\}$;
(2) Let $S_{n}$ be the sum of the first $n$ terms of the sequence $\{a_{n}\}$, and let $b_{n} = \frac{1}{S_{3n}}$. Find the sum of the first $n$ terms of the sequence $\{b_{n}\}$, denoted as $T_{n}$.

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