题解 | #等差数列#

import java.util.Scanner;
public class Main{
    public static void main(String[] args){
        Scanner scan=new Scanner(System.in);
        while(scan.hasNextInt()){
            System.out.println(getSum(scan.nextInt()));
            System.out.println(getSum(scan.nextInt()));
        }
    }
    public static int getSum(int n){
        int num=2;
        int sum=0;
        for(int i=1;i<=n;i++){
            sum+=(num+(i-1)*3);
        }
        return sum;
    }
    public static int getSum1(int n){
        int a1=2;
        int an=a1+(n-1)*3;
        return n*(a1+an)/2;
    }
}