题解 | #等差数列#
等差数列
http://www.nowcoder.com/practice/f792cb014ed0474fb8f53389e7d9c07f
等差数列求和公式
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while (sc.hasNext()) {
int number = Integer.parseInt(sc.nextLine().trim());
int a1= 2,d =3;
System.out.println(number*a1+(number-1)*number*d/2);
}
}
}