
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 the ellipse be $\dfrac {x^{2}}{a^{2}}+ \dfrac {y^{2}}{b^{2}}=1(a > b > 0)$, and the line $l$: $y=kx+m(m\neq 0)$ intersects the ellipse at points $A$ and $B$. When $l$ passes through a focus and a vertex of the ellipse, $k=m= \sqrt {3}$.  
(Ⅰ) Find the equation of the ellipse;  
(Ⅱ) If the slopes of lines $OA$, $AB$, and $OB$ form an arithmetic sequence (where $O$ is the origin), find the maximum area of $\triangle OAB$.

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