I don't think there is such a command. Depending on how your distro has set things up you could take a look in the udev rules (/etc/udev/ ???). Or if you have a pre-udev system, there could be a file called makedev somewhere on your box, which could hold this info.
BTW: These major and minor numbers are fixed and distro independent. You could look on-line for the makedev script.
Hope this helps.