4 2 6 3 10 ?

Group the sequence in pairs. Look at the first number, then the second in each pair. Isn't the second one half the first?
So, what is half of 10?

Or it could be something like:

(4, 2), (6, 3), (10, )

Where the 'x' is increasing by 2, 4, 6, 8, etc and 'y' increasing by 1.