I have a list of time (seconds) that looks like that:

l = [2,4,6,8,2,4,6,8,10,30,60,30,60]

2,4,6,8 is the first time interval.2,4,6,8,10 the second, 30,60 the third,30,60 the forth.

I would like to create a list of time like below so i can plot the data:

l = [2,4,6,8,10,12,14,16,18,48,78,108,138]