# Attractive

Calculus Level 5

$\large \frac{\left(1^4 + \frac14\right)\left(3^4 + \frac14\right)\cdots \left((2n-1)^4 + \frac14\right)}{\left(2^4 + \frac14\right)\left(4^4 + \frac14\right)\cdots \left((2n)^4 + \frac14\right)}$

Given that the expression above can be simplified to $$(an^2+ bn + c)^{-1}$$ for constants $$a,b,c$$, find $$21(a-b+c)$$.

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