
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]


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Given an arithmetic sequence ${a_n}$ with a common difference $d < 0$, and knowing that $a_2 + a_6 = 10$, $a_2 \cdot a_6 = 21$:

(Ⅰ) Find the general term formula for the sequence ${a_n}$;  
(Ⅱ) Let $b_n = 2^{a_n}$, and denote the product of the first $n$ terms of the sequence ${b_n}$ as $T_n$. Find the maximum value of $T_n$.

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