
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
Write down the general formula for the following sequences:  
(1) $\frac {1}{2}$, $\frac {1}{6}$, $\frac {1}{12}$, $\frac {1}{20}$,…;  
(2) 1, 2, 4, 8,…;  
(3) $\frac {4}{5}$, $\frac {1}{2}$, $\frac {4}{11}$, $\frac {2}{7}$,…．

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