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PUMaC 2015 · 团队赛 · 第 1 题

PUMaC 2015 — Team Round — Problem 1

专题
Discrete Math / 离散数学
难度
L3
来源
PUMaC

题目详情

  1. [ 2 ] Let f ( n ) denote the sum of the distinct positive integer divisors of n . Evaluate: f (1) + f (2) + f (3) + f (4) + f (5) + f (6) + f (7) + f (8) + f (9) .
解析
  1. [ 2 ] Let f ( n ) denote the sum of the distinct positive integer divisors of n . Evaluate: f (1) + f (2) + f (3) + f (4) + f (5) + f (6) + f (7) + f (8) + f (9) . Solution: The expression evaluates to: 1 + 3 + 4 + 7 + 6 + 12 + 8 + 15 + 13 = 69 Author: Bill Huang