
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 vectors $$\overrightarrow {a}=(2, -n)$$ and $$\overrightarrow {b}=(s, n+1)$$, where $n \in \mathbb{N}^*$ and $s$ is the sum of the sequence $\{a_n\}$ up to the $n$-th term. If $$\overrightarrow {a} \perp \overrightarrow {b}$$, then the maximum value of the sequence $$\left\{ \frac {a_{n}}{a_{n+1}a_{n+4}}\right\}$$ is \_\_\_\_\_\_.

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