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Problem:
Given a formula:
GCD(x,y) means the GCD (Greatest Common Divisor) of x and y.
For example: if N=2, then:
f(2) = 1/GCD(1, 4) + 2/GCD(2, 4) + 3/GCD(3, 4) + 4/GCD(4,4)
f(2) = 1/1 + 2/2 + 3/1 + 4/4
f(2) = 1 + 1 + 3 + 1
f(2) = 6
Given N, find f(N)!
Simplified formula that I found us...