
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 sum of the first $n$ terms of the sequence $1,(1+2),\left(1+2+2^{2}\right), \cdots,\left(1+2+2^{2}+\cdots+2^{n-1}\right)$, expressed in terms of $n$, is given by $2^{n}$.

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