
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 $\{a_n\}$ is an arithmetic sequence, and $a_3+a_4=8$, $a_2+4=a_4$; the sequence $\{b_n\}$ satisfies: $b_n= \frac {1}{a_{n+1}a_{n+2}}$.  
(I) Find the general formula for the sequence $\{a_n\}$.  
(II) Let the sum of the first $n$ terms of the sequence $\{b_n\}$ be $S_n$, if $\frac {S_n}{n+1} > \frac {1}{20}$, find the maximum value of $n$.

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