MathDB
Math Prize 2013 Problem 4

Source:

September 10, 2013

Problem Statement

The MathMatters competition consists of 10 players P1P_1, P2P_2, \dots, P10P_{10} competing in a ladder-style tournament. Player P10P_{10} plays a game with P9P_9: the loser is ranked 10th, while the winner plays P8P_8. The loser of that game is ranked 9th, while the winner plays P7P_7. They keep repeating this process until someone plays P1P_1: the loser of that final game is ranked 2nd, while the winner is ranked 1st. How many different rankings of the players are possible?