The gcd of $x^n-1$ and $x^m-1$ is $x^{gcd(n,m)}-1$. Is it known what the greatest common divisor of $(x^{n_1}-1)(x^{n_2}-1)$ and $(x^{m_1}-1)(x^{m_2}-1)$ is?
The gcd of $x^n-1$ and $x^m-1$ is $x^{gcd(n,m)}-1$. Is it known what the greatest common divisor of $(x^{n_1}-1)(x^{n_2}-1)$ and $(x^{m_1}-1)(x^{m_2}-1)$ is?