原题传送门

1. 题目描述

2. Solution

import sys

def solve(n):
    a1 = 2
    d = 3
    print(a1 * n + n * (n - 1) * d // 2)

for line in sys.stdin:
    n = int(line.strip())
    solve(n)

标签：sys,原题,int,a1,牛客,solve,机试,HJ100,line
来源： https://www.cnblogs.com/junstat/p/16181407.html