
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 $\{a\_n\}$, the sum of its first $n$ terms is $S\_n$, and it satisfies $S\_5 - S\_2 = 21$, $2a\_2 - a\_4 = -1$.
(1) Find the general term formula of the sequence $\{a\_n\}$;
(2) If $b\_n = a\_{2^{n}}$, find the expression for the sum of the first $n$ terms of the sequence $\{b\_n\}$.

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