Find the smallest $n>3$ such that $(1+2+3+\cdots+n)^2$ is a perfect fourth power.
Question:
Find the smallest $n>3$ such that $(1+2+3+\cdots+n)^2$ is a perfect fourth power.
Answer:
Let's think step by step.

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Find the smallest $n>3$ such that $(1+2+3+\cdots+n)^2$ is a perfect fourth power.
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