题解 | #等差数列#
等差数列
https://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
#include<stdio.h> int main() { int n = 0; scanf("%d", &n); int arr[1000] = { 2 }; int m = 0; for (int i = 0; i < n; i++) { arr[i + 1] = arr[i] + 3; } for (int i = n; i > 0; i--) { m += arr[n-i]; } printf("%d", m); return 0; }