
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
For a positive integer $n$, let the curve $y=x^{n}(1-x)$ have a tangent at $x=2$, which intersects the $y$-axis at a point with ordinate $a_{n}$. Find the formula for the sum of the first $n$ terms of the sequence $\left\{ \frac {a_{n}}{n+1} \right\}$.

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