
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
A sequence of $6$ numbers is formed by starting with two initial numbers. Each subsequent number in the sequence is the product of the two previous numbers. Given that the last two numbers of the sequence are $81$ and $6561$, find the value of the first number in the sequence.

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