
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
The Fibonacci sequence ${a_n}$ has its first two numbers as 1, and from the third number onwards, each number is equal to the sum of the two preceding ones. If $b_n = a_n a_{n+2} - a_{n+1}^2$, then find the value of $b_1 + b_2 + b_3 + ... + b_{2019}$.

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