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Let $\phi_{n}(x)$ be the $n$-th cyclotomic polynomial. What are the restrictions to $n$ (if any) to have $\phi_{n}(x)$ divides $\phi_{2n}(x)$ (where division is in $\mathbb{Z}[x]$)?\mathbb{Z}[x]$)?Or is it true that $\frac{\phi_{2n}(x)}{\phi_{n}(x)}\in\mathbb{Z}[x]$ for all integers $n$?

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Let \phi_{n} $\phi_{n}(x)$ be the n-th $n$-th cyclotomic polynomial. What are the restriction restrictions to n $n$ (if any) to have \phi_{n} $\phi_{n}(x)$ divides \phi_{2n} ?$\phi_{2n}(x)$ (where division is in $\mathbb{Z}[x]$)?

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Cyclotomic Polynomials

Let \phi_{n} be the n-th cyclotomic polynomial. What are the restriction to n (if any) to have \phi_{n} divides \phi_{2n} ?