Some venues have their rows set in a way that every other has odd or even numbers. Manually labeling seats one by one to match this condition would be quite time consuming and painstaking job so we've integrated to our Seating Charts add-on a possibility to automate this.
Let's say that your row has ten seats and that these seats should have odd numbers (1, 3, 5, 7,...). To label seats like this in Seating Charts you will have to select that row (after assigning it with the ticket type of your choice) and then set starting number as 1 and ending number as 19 and hit the Assign button. Seating Charts add-on will then calculate this number span and distribute it evenly having as the end result all the seats with odd numbers.
Same goes for the even numbers where you should enter 2 as starting number and 20 as ending number.
Also, you might wonder what would happen if you set starting number as 1 but set the ending number as 30 in the ten seats row. Although we certainly encourage you to try this and see for yourself, the result will be also evenly distributed seat numbers so you will have seat numbers in the pattern of 1, 4, 7, 10,....
In any case, prefix letter has no effect on the pattern.