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Recently I was studying math and came across this problem:
Given 1 < a < 10, 1 <= n <= 100000, show how to compute the value of: 1 * a + 2 * a^2 + 3 * a^3 + ... + n * a^n efficienty, i.e. in O(log n)!
Could someone give ideas/way to solve this problem?
