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Problem 565


Problem 565


Divisibility of sum of divisors

Let σ(n) be the sum of the divisors of n.
E.g. the divisors of 4 are 1, 2 and 4, so σ(4)=7.

The numbers n not exceeding 20 such that 7 divides σ(n) are: 4, 12, 13 and 20, the sum of these numbers being 49.

Let S(n,d) be the sum of the numbers i not exceeding n such that d divides σ(i).
So S(20,7)=49.

You are given: S(106,2017)=150850429 and S(109,2017)=249652238344557.

Find S(1011,2017).


约数和的整除性

σ(n)为n的约数的和。
例如4的约数为1,2和4,因此σ(4)=7

在不超过20的数n中,σ(n)能被7整除的有4,12,13和20,这些数的和是49。

记S(n,d)是所有不超过n且σ(i)能被d整除的数i的和。
因此S(20,7)=49。

已知S(106,2017)=150850429以及S(109,2017)=249652238344557

S(1011,2017)


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