
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
The sequence $\{a\_n\}$ satisfies $a\_1+3a\_2+3^{2}a\_3+…+3^{n-1}a\_n= \frac {n}{2}$, and the sum of the first $n$ terms is $S\_n$. Find $S\_n$.

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