|As you have found, you can't use a number as a Range Name.|
You can however, still use numbers in your primary Drop Down to populate your Dependent Drop Downs.
I am assuming that you plan to use the standard method of creating Dependent Drop Down, specifically Named Ranges and the INDIRECT function.
Let's say your primary Drop Down is in A1.
Name your Dependent ranges List1, List2, ... List14
Then, for the Dependent Drop Down use =INDIRECT("List" & A1)