2018-2019 Fall OMO Problem 9
Source:
November 7, 2018
Problem Statement
Ann and Drew have purchased a mysterious slot machine; each time it is spun, it chooses a random positive integer such that is chosen with probability for every positive integer , and then it outputs tokens. Let be a fixed integer. Ann and Drew alternate turns spinning the machine, with Ann going first. Ann wins if she receives at least total tokens from the slot machine before Drew receives at least total tokens, and Drew wins if he receives tokens before Ann receives tokens. If each person has the same probability of winning, compute the remainder when is divided by .Proposed by Brandon Wang