
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 the sequence of even counting numbers, find the sum of the first 1500 terms, and then find the sum of the first 1500 odd counting numbers. Add this result to the sum of the first 1500 triangular numbers.

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