I don't often make MindMaps that use markers beyond the number 6, but I did need them for a special project. I looked all over the web, but could not find any marker packages, so I decided to make my own.
As I side note, does anyone know of a repository of marker packages?
Attached is a marker package with yellow on blue numbers --- 1 through 25. I threw in the letters A through H and some miscellaneous symbols, too. Feel free to download and use as you wish with my compliments.