Dato un primo $p$ dispari, mostrare che
$$
\sum_{k = 1}^{p-1} k^{2p-1} \equiv \binom{p+1}{2} \pmod{p^2}.
$$
$\sum k^{2p-1}$ modulo $p^2$
$\sum k^{2p-1}$ modulo $p^2$
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