题解 | #等差数列#
等差数列
https://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
找规律
#include <stdio.h>
int main()
{
int n = 0;
int sum = 0;
int i = 0;
scanf("%d",&n);
for(i=0; i<n; i++)
{
sum += 2+i * 3;
}
printf("%d\n",sum);
return 0;
}