876pol daniel_wang123 advey orz

~n~th cyclotomic polynomial

$$\displaystyle \Phi_n (x) = \prod_{1\le k\le n \atop \gcd(k,n)=1} \left(x-e^{\frac{2i \pi k}{n}} \right)$$

The Law of Quadratic Reciprocity

If ~p~ and ~q~ are distinct odd primes, $$\displaystyle \left(\frac{p}{q}\right) \cdot \left(\frac{q}{p}\right) = (-1)^{\frac{(p-1)(q-1)}{4}}.$$

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