
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 the general term formula of the sequence $\{a_n\}$ as $$a_{n}= \begin{cases} \frac {1}{n(n+2)}，n\text{ is odd} \\ n-7，n\text{ is even}\end{cases}$$, find the value of the sum of the first 15 terms of the sequence, denoted as $S_{15}$.

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