4, 8, 9, 10, 12, 16, 18, 20, 24, 25, 27, 28, 30, 32, 36.
and it ends there.
the problem is thinking you start with 4, you don't.
you start with 16, and focus on 20.
16+4(the first number)=20
then it follows
16+8=24
16+9=25
then, after 3 you jump to 18 and skip the first 2...