
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
During an early morning drive to work, Simon encountered \( n \) sets of traffic lights, each set being red, amber, or green as he approached it. He noticed that consecutive lights were never the same colour. Given that he saw at least two red lights, find a simplified expression, in terms of \( n \), for the number of possible sequences of colours Simon could have seen.

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