
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 a sequence ${a_n}$ satisfying $a_1 = 1$ and $a_{n-1} = 2a_n$ (where $n \geq 2$, $n \in \mathbb{N}^+$), calculate the sum of the first 6 terms of the sequence ${a_n}$.

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