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「QQ红包」
2017-12-08 20:22:54
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$$
\begin{eqnarray}
ans=\sum \limits \_{i=1} ^{k} \bigg(\sum \_{d=1}^{i} \mu \big(d\big)\bigg\lfloor \frac{i}{d} \bigg\rfloor ^{n} \bigg)\oplus i\\
\end{eqnarray}
$$