
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 seven-digit telephone number $a_1a_2a_3a_4a_5a_6a_7$, if the sequence of the first three digits $a_1a_2a_3$ is the same as either $a_4a_5a_6$ or $a_5a_6a_7$ (it's possible that all three are the same), then this number is considered "memorable". If $a_1, a_2, \ldots, a_7$ can each be any digit from 0, 1, 2, ..., 9, then the total number of different "memorable" numbers is     .

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