Numbers: how do I create a column with a sequence of times? In Numbers, I would like to create a column with automatically generated cells to create a timetable with each hour and each half hour.

I create a new document, type in "7:30 AM" and then in the cell below I type in "8:00 AM" then I drag downwards from the first cell, but it doesn't work, it replaces "8:00 AM" by "8:30 AM" but I only want 30 mns increments...



I tried changing the cell format to "date and time" but it just erases whatever I typed and replaces it by today's date and time or random dates and times...
The formula syntax in Numbers is actually less intuitive and more stubborn than Excel IMO. Nevertheless, to create time intervals:


In the first cell, say B2, type 8:00 AM
In the following cell, type =B2+"30m"


Now, drag down:


Voilà: