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Problem #7

Exponentiation

f(x,n) = x^{2^1} + x^{2^2} + x^{2^3} + ... + x^{2^n}

You are given that f(2,10) \mod 1000000007 = 180974681

Calculate \sum\limits_{x=2}^{10^7} f(x,10^{18}) \mod 1000000007

Contributed by Sai Teja

Solved by 46 users

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