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The Lane-Emden equation is typically written as $$\frac{1}{\xi^2} \frac{d}{d\xi} \left( \xi^2 \frac{d\theta}{d\xi} \right) = -\theta^n,$$ which makes sense given the derivation on the Wikipedia page. But, why not keep going with the simplification?
$$\begin{align*}
\frac{1}{\xi^2} \frac{d}{d\xi}...