题解 | #等差数列#
等差数列
https://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
import java.util.Scanner; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { public static void main(String[] args) { Scanner in = new Scanner(System.in); int n=in.nextInt(); int[] arr=new int[n]; arr[0]=2; int res=2; for(int i=1;i<n;i++){ arr[i]=arr[i-1]+3; res+=arr[i]; } System.out.print(res); } }