Chapter 6 Exercise 1, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

6.1 (Math: pentagonal numbers) A pentagonal number is defined as n(3n–1)/2 for n = 1, 2, . . ., and so on. Therefore, the first few numbers are 1, 5, 12, 22, . . . . Write a method with the following header that returns a pentagonal number: public static int getPentagonalNumber(int n) Write a test program that uses this method to display the first 100 pentagonal numbers with 10 numbers on each line.

public class ProgrammingExercise6_1 {
 
 public static void main(String[] args) {
  for (int i = 1; i <= 100; i++) {
   System.out.printf("%8d", getPentagonalNumber(i));
   if (i % 10 == 0) {
    System.out.println("");
   }
 
  }
 
 }
 
 public static int getPentagonalNumber(int n) {
  return n * (3 * n - 1) / 2;
 }
 
}