# Infinite sum question

Calculus Level 4

$\large \dfrac{1^3}{3^1} + \dfrac{2^3}{3^2} + \dfrac{3^3}{3^3} + \dfrac{4^3}{3^4} + \cdots$

If the series above is equal to $$\dfrac pq$$, where $$p$$ and $$q$$ are coprime positive integers, find $$p+q$$.

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