binaryNialpdromes.java

public static List<Long> binaryNialpdromes(int n) {
    final var ret = new ArrayList<Long>(n*(n+1)/2);

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < i; j++) {
            ret.add((long) (Math.pow(2.0, i) - Math.pow(2.0, j)));
        }
    }

    return ret;
}