class GeometricProgression {
 
    public static void main(String[] args) {
        final int[] a = new int[] { 1, 2, 3, 6, 18, 22 };
        geoProgression(a);
    }
 
    private static void geoProgression(int[] a) {
        // loop to all elements
        for (int i = 0; i < a.length - 3; i++) {
            int element = a[i];
            for (int j = i + 1; j < a.length; j++) {
                int target = a[j];
                if (target % element == 0) {
                    int r = target / element;
                    int possibleNext = r * target;
                    int k = j + 1;
                    // find out if possible next exists
                    while (k < a.length) {
                        int pp = a[k++];
                        if (pp == possibleNext) {
                            System.out.println(element + " " + target + " " + possibleNext);
                            break;
                        }
                    }
                }
            }
        }
    }
}

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