Sounds like an Austrian newspaper stamp. In that case, the year range and ID number given suggest that the N5 is the design number, not the catalog number.
Used stamps of design N5 range from 40c to $32.50 (ignoring EFOs) in 2009 Scott catalog. To ID properly, there needs to be a very high resolution pic to ID the proper Die Type. Even with that, the color variations are almost impossible to distinguish from a scan (at least I can't -- I have to compare side-by-side with my reference stamps).
Fun stamp to have. Nice simple but attractive design.

k