I realize this is not a question specifically about the Italian language, so I apologize if this is the wrong place to ask. I see many Italian dates written to include "n. xxxx" at the end. For example, 12 November 1818, n. 1379. What do the numbers after n. refer to?
It simply means numero (number) since it is commonly used when you have more than an occurrence of a certain event during the same day.
Think about, for example, an hospital registering newborn children.
Actually the “n.” and what follows is not actually part of the date. It might well appear before it, or somewhere else in the same document.
Also, on newspapers and magazines and periodic publications in general that "n. xxx", preceded or followed by a date, is the equivalent of "issue (nr.) xxx". In those cases, it is not unusual to see it followed by Roman numerals (e.g. "n. 12" or "n. XII")