public static int numberOfBuckets(int indexBitLength)
    {
        return 1 << indexBitLength;
    }
@Test
    public void testNumberOfBuckets()
    {
        for (int i = 1; i < 20; i++) {
            assertEquals(SfmSketch.numberOfBuckets(i), Math.round(Math.pow(2, i)));
        }
    }