
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
Given the sequence $\{a_n\}$, where $a_1=3$, and $na_{n+1}-a_n=na_n$.
(I) Find the general term formula for the sequence $\{a_n\}$;
(II) Let $S_n$ denote the sum of the first $n$ terms of the sequence $\{a_n\}$, find the sum of the first $n$ terms, $T_n$, of the sequence $\{ \frac {1}{S_{n}}\}$.

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