n=4: |Q_n| = 2^8, kernel = [(1, 0, 0), (9, 0, 8)], |image| = 2^7, involutions of image = 43
n=5: |Q_n| = 2^11, kernel = [(1, 0, 0), (17, 0, 16)], |image| = 2^10, involutions of image = 167
n=6: |Q_n| = 2^14, kernel = [(1, 0, 0), (33, 0, 32)], |image| = 2^13, involutions of image = 647
n=7: |Q_n| = 2^17, kernel = [(1, 0, 0), (65, 0, 64)], |image| = 2^16, involutions of image = 2567
