HMMT 二月 2001 · 冲刺赛 · 第 36 题
HMMT February 2001 — Guts Round — Problem 36
题目详情
- [4] Count the number of sequences 1 ≤ a ≤ a ≤ · · · ≤ a of integers with a ≤ i 1 2 5 i for all i .
解析
- [4] Count the number of sequences 1 ≤ a ≤ a ≤ · · · ≤ a of integers with a ≤ i 1 2 5 i for all i . Solution: C (number of terms) = C (5) = 42 .