题解 | #牛牛学数列4#
牛牛学数列4
https://www.nowcoder.com/practice/586b114f52034688879342ba45779081
#include <stdio.h>
int main()
{
int n = 0;
scanf("%d", &n);
int i = 0;
int sum = 0;
for (i = 1; i <= n; i++)
{
sum += (1 + i) * i / 2;//等差数列前n项和公式
}
printf("%d\n", sum);
return 0;
}