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Problem #141

Complex Summation

An nth root of unity, where n is a positive integer (i.e. n = 1, 2, 3, …), is a number z satisfying the equation:

z^n = 1

An nth root of unity is primitive if it is not a kth root of unity for some smaller k:

z^k \neq 1 (k = 1,2,3,...,n-1)

Let S(n) be the sum of all the primitive nth roots of unity.

Define F(n,k) = \sum_{i=1}^{n} i^k S(i)

Enter the value of F(10^{11},10^3) mod 1000000007.

Contributed by Adarsh Kumar

Solved by 10 users

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