How can I perform this code:

if a number n is divisible by 3, add 4 to n;
if n is not divisible by 3 but by 4, divise n by 2;
if n is not divisible by 3, not by 4, make n=n-1.

The problem with me is that I don't know how to make this successively. For example: with the number 6, I have to have:

6, 10, 9, 13, 12, 16, 8, 4, 2, 1 et 0

6+4=10; 10-1=9; 9+4=13; 13-1=12; 12+4=16; 16/2=8.....0

This makes 10 operations.

So my program has to return: 6---10

Thank you for help