9, 9(2)=18, 9(3)=27, 9(4)=36 9(5)=45
9,18,27,36,45……..144
Not sure if this is what you are looking for. If the number of blanks is the amount of numbers allowed then the above will not work
9(13)=117, 9(14)=126, 9(15)= 135, 144
If you can only have 3 blanks then the second one could work.
Again, not sure if this is what you need. But hopefully it helps.
