For any 2 members, add their least common multiple to the set, if and only if it was not already in the set.
Continue the task until it cannot be done.
Call the result a final list.
a. (2,4,8,16) a is a final list.
b. (2,3,4,6) will become a final list once we add number 12 to the set.
What can be the longest final list, if the initial set had 10 distinct numbers?