In number theory, Euler's totient function φ(n) counts the positive integers up to a given integer n that are relatively prime to n. It can be defined more form...

Problem DescriptionWhen Teddy was a child , he was always thinking about some simple math problems ,such as “What it’s 1 cup of water plus 1 pile of dough ..” ...

There are an equation. ∑0≤k1,k2,⋯km≤n∏1⩽j<m(kj+1kj)%1000000007=? We define that (kj+1kj)=kj+1!kj!(

Problem Description Ignatius is poor at math,he falls across a puzzle problem,so he has no choice but to appeal to Eddy. this problem describes that:f(x)=5x13+...

Problem Description 有N个比赛队（1<=N<=500），编号依次为1，2，3，....，N进行比赛，比赛结束后，裁判委员会要将所有参赛队伍从前往后依次排名，但现在裁判委员会不能直接获得每个队的比赛成绩，只知道每场比赛的结果，即P1赢P2，用P1，P2表示...

Giving the N, can you tell me the answer of F(N) Input Each test case contains a single integer N(1<=N<=10^9). The input is terminated by a set starting with N...

RXD is a good mathematician. One day he wants to calculate:

A cubic number is the result of using a whole number in a multiplication three times. For example, 3×3×3=27 so 27 is a cubic number. The first few cubic number...

首先，在不设置 repeat 参数的时候，默认是1，生成的list长度时6 —— 这可以用数学的排列组合来表示，从第一个参数[‘西藏’,’瀑布’,’湖水’]取出一个值，有3种可能；从第二个参数[‘月色’,’星空’]取出一个值，有2种可能；故 ...

Description 通常把在 n 个排好序的数中，位于最中间的数就走“中位数”，这里再规定细一点，如果 n 是奇数，那么最中间的数只有一个，那就是“中位数”，但如果 n 是偶数，那么最中间的数有两个，我们把这两个数的平均数也叫作“中...