
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 function f(n) = $$\begin{cases} -n^{2},  n\text{ is odd} \\ n^{2},  n\text{ is even}\end{cases}$$, and a<sub>n</sub> = f(n) + f(n+1), find the sum of the sequence a<sub>1</sub> + a<sub>2</sub> + a<sub>3</sub> + ... + a<sub>2018</sub>.

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