
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 $\{a_n\}$ that satisfies $a_0 = 1$ and $a_n = a_0 + a_1 + ... + a_{n-1}$ for $n \geqslant 1$, determine the value of $a_n$ when $n \geqslant 1$.

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