“…). If f 1 = x − 1 then we consider the following cases: Similarly, conditions (1), (3), (4), and (9) imply f 4 | k 2 , conditions (1), (3), (4), (5), (9), (10), and (13) imply f 5 | k 3 , conditions (1), (3), (4), (5), (6), (9), (10), (13) and (16) imply f 6 | k 4 , conditions (1), (3), (4), (5), (6), (7), (9), (10), (12), (13), (14), (16), (17), and (18) imply f 7 | k 5 , conditions (1), (3), . .…”