
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
Using the digits $1, 3, 5, 7, 9$, form an $n$-digit number with the requirement that the digits 3 and 7 appear an even number of times, while the other three digits have no restrictions. How many such numbers can be formed?

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