public class TriangularStars {

	public static boolean isStarNumber (long number)
	{
		for (int n = 0; n <= Math.sqrt(number); n++)
		{
			long starNumber = (((6 * n) * (n - 1)) + 1);
			if (starNumber == number)
			{
				return true;
			}
		}
		return false;
	}

	public static long determineTriangleNumber (int number)
	{
		long triangleNumber = number;
		long lastTriangleNumber = triangleNumber;
		for (int n = 0; n < number ; n++) {
			triangleNumber = lastTriangleNumber + n;
			lastTriangleNumber = triangleNumber;
		}
		return triangleNumber;
	}

	public static void main (String[] args)
	{
		long triangleNumber = 0;
		for (int n = 0; triangleNumber < Integer.MAX_VALUE; n++)
		{
			triangleNumber = determineTriangleNumber(n);
			boolean isStarNumber = isStarNumber(triangleNumber);
			if (isStarNumber == true)
			{
				System.out.println(triangleNumber + " is both a star number and a triangle number");
			}
		}
	}
}