Interessant - ist mir gar nicht aufgefallen:
Lost-Numbers
The numbers were featured in the episode Lighthouse when Jack learned that if the Lighthouse mirror were turned to a certain degree, it would show the lives of a particular person. The people who were shown at 4, 8, 15, 16, 23, and 42 were the remaining candidates to replace Jacob, explaining why the names were grouped together with those numbers in Jacob's cave. (The only exception to this is Kate, whose corresponding number 51 is not one of the original sequence).