題目網址: http://www.puzzleup.com/2018/
http://www.puzzleup.com/2018/puzzle/?9
答題時限: 9月27日7PM-比賽結束(約12月12日)
加分時限: 9月27日7PM-10月3日6:59PM
答對可得基本分100分。答案可上傳5次,每改1次答案從基本分扣20分。
比賽期間內可隨時上傳答案,加分時限內答對第n天加(6-n)分
另依題目的難易有額外加分(如有80%的人這題答錯,答對者加80分)
◆ABUNDANT NUMBER
An abundant number is a positive integer for which the sum of its proper
divisors (positive divisors different than the number) exceeds the number
itself. For example, 18 is an abundant number (18<1+2+3+6+9).
How many consecutive positive integers must be selected at minimum, in
order to guarantee that at least one of the selected numbers is abundant?
所謂過剩數為一正整數,其真因數(與該數不同之正因數)總和超過該數本身者。
舉例來說,18便是個過剩數(18<1+2+3+6+9)。
問至少要連續取多少正整數,才能保證其中必有過剩數?