Populating lists with duplicate items - Urgent help needed

Hey guys, I'm looking for help with a list-related issue.

I need to create a list to control a bline/line object. This list will contain target values and time durations - forget the target values for now. To create the list, I want to use the combination of two other lists: one contains time values and the other contains the number of their occurrences in order. E.g.:
time values: (2000, 1000, 500, 250)
occurrences: (2, 3, 2, 4)
My desired result: (2000, 2000, 1000, 1000, 1000, 500, 500, 250, 250, 250, 250)

I've been looking at the zl modes but I couldn't seem to find anything related to specify the number of occurrences of an item.
Any pointers would be greatly appreciated.
Thanks in advance.

Benji