Can you fill in the missing numbers of these number sequences?
_, 3, _, 9, _, 14, _, _, 21, 27, _, 35, _
_, 7, _, 15, _, 22, _, 30
_, _, 5, 7, _, _, 12
The three sequences may or may not be linked together in some way. If you can come up with the missing numbers, please provide an explanation.
I have tried to solve this for about a week now and I've gotten nowhere, hopefully someone here comes up with something.