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  • SDOI2017数字表格

    求$prod_{i=1}^nprod_{j=1}^n ext{Fib}[gcd(i,j)]; ext{mod};10^9+7$的值
    令$nleq m$,则有:

    egin{aligned}
    prod_{i=1}^nprod_{j=1}^nf[gcd(i,j)]
    &=prod_{d=1}^nprod_{i=1}^frac ndprod_{j=1}^frac md ext{Fib}[d]^{[gcd(i,j)=1]}\
    &=prod_{d=1}^n ext{Fib}[d]^{sum_{i=1}^nsum_{j=1}^m[gcd(i,j)=d]}\
    &=prod_{d=1}^n ext{Fib}[d]^{sum_{i=1}^{leftlfloorfrac nk ight floor}sum_{j=1}^{leftlfloorfrac mk ight floor}sum_{k|gcd(i,j)}mu(k)}\
    &=prod_{d=1}^n ext{Fib}[d]^{sum_{i=1}^{leftlfloorfrac nk ight floor}sum_{j=1}^{leftlfloorfrac mk ight floor}sum_{k|i}sum_{k|j}mu(k)}\
    &=prod_{d=1}^n ext{Fib}[d]^{sum_{i=1}^{leftlfloorfrac nk ight floor}sum_{k|i}sum_{j=1}^{leftlfloorfrac mk ight floor}sum_{k|j}mu(k)}\
    &=prod_{d=1}^n ext{Fib}[d]^{sum_{i=1}^{minleft(leftlfloorfrac nk ight floor,leftlfloorfrac mk ight floor ight)}mu(k)sum_{i=1}^{leftlfloorfrac nk ight floor}sum_{k|i}sum_{j=1}^{leftlfloorfrac mk ight floor}sum_{k|j}1}\
    &=prod_{d=1}^n ext{Fib}[d]^{sum_{i=1}^{minleft(leftlfloorfrac nk ight floor,leftlfloorfrac mk ight floor ight)}mu(k)sum_{i=1}^{leftlfloorfrac nk ight floor}sum_{k|i}1sum_{j=1}^{leftlfloorfrac mk ight floor}sum_{k|j}1}\
    end{aligned}

    ...To be continue.

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  • 原文地址:https://www.cnblogs.com/TheRoadToAu/p/7583056.html
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