
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
Let S<sub>n</sub> be the sum of the first n terms of the arithmetic sequence {a<sub>n</sub>}, given that a<sub>7</sub> = 5 and S<sub>5</sub> = -55.

1. Find S<sub>n</sub>.
2. Let b<sub>n</sub> = $$\frac {S_{n}}{n}$$, find the sum of the first 19 terms, T<sub>19</sub>, of the sequence { $$\frac {1}{b_{n}b_{n+1}}$$}.

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