# Infinite sum

Calculus Level pending

$\large \sum_{j=0}^\infty (3j+2)^3 x^{j+1}$

If the series above converges and can be expressed as $$\dfrac{x(x^3 - ax^2 + bx + c)}{(x-1)^4}$$ for a constant $$x$$. Find the value of $$a$$.

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