
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
Given that the sum of the first $n$ terms of an arithmetic sequence $\{a_n\}$ is $S_n$ and that $S_5=45$ and $S_6=60$.  
(Ⅰ) Find the general term formula $a_n$ for the sequence $\{a_n\}$.  
(Ⅱ) If the sequence $\{b_n\}$ satisfies $b_{n+1}-b_n=a_n$ (where $n\in\mathbb{N}_+$) and $b_1=3$, find the sum of the first $n$ terms $T_n$ of the sequence $\left\{ \frac{1}{b_n} \right\}$.

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