Sum of Natural Numbers which are Divisible by 3 or 5

import java.util.Scanner;

public class SumOf_n_NaturalNumbers {
	public static void main(String[] args) {
		int n;
		Scanner input = new Scanner(System.in);
		System.out.println("Enter Number :");
		n = input.nextInt();
		calculate_Sum(n);
	}

	public static void calculate_Sum(int n) {
		int i = 1, sum = 0;
		if (n % 3 == 0 || n % 5 == 0) {
			do {
				sum = sum + i;
				i += 1;
			} while (i <= n);
			System.out.print("Sum of First " + n + " Numbers = " + sum);
		} else

			System.out.print("not divisble by 3 or 5");
	}

}

Result:
Input: Enter Number 4
Ouput: not divisble by 3 or 5