Suppose that p = 87k +4 is prime prove
(29/p)=1
As is easy to see that $\displaystyle p\equiv 4\!\!\!\pmod {29}$ and $\displaystyle 29\equiv 1\!\!\!\pmod 4$, we get by Gauss that $\displaystyle \left(\begin{array}{c}29\\p\end{array}\right)=\lef t(\begin{array}{c}p\\29\end{array}\right)=\left(\b egin{array}{c}4\\29\end{array}\right)=1$
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