
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
In the sequence $\left\{a_n\right\}$, $a_1=8, a_4=2$, and it satisfies $a_{n+2}-2a_{n+1}+a_n=0$.  
(1) Find the general formula for the sequence $\left\{a_n\right\}$.  
(2) Let $T_n=|a_1|+|a_2|+|a_3|+\cdots+|a_n|$, and find the expression for $T_n$.

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