I am looking at the declension tables for 'jeder' here. I'm confused why the 'with indefinite article' portion of the table exists. That is, when would you ever say something like 'a/an every/each [something]'? I am a native English speaker and the only (weak) parallel I can draw is something like the awkward and possibly incorrect 'This is an everybody occasion' (same meaning as the much more common and obviously correct 'This is an occasion for everybody') and similar awkward constructions.
German and English are both west-germanic languages, so they are closely related to each other and have many features in common. But there are also hundreds of grammatical features that are different, and where you can't find parallels in the other language.
The construction »ein jeder« is such a case without parallels in English. In English you have only »everybody« or »each«, but German allows both: »jeder« as well as »ein jeder«.
Both versions are interchangeable and they mean quite the same. Adding the article just emphasizes the fact, that really everyone (without any exception) is meant. Depending on context, the version without articles could also be interpreted as »everybody, with some few exceptions«. »Ein jeder« points out, that exceptions are very unlikely.
But »ein jeder« is less often used, and in most cases »jeder« (without article) is better style (very often »ein jeder« is really bad style).
This also works in other genders, not only male:
- female (die Münze / the coin = female)
Eine jede Münze hat zwei Seiten. (bad style)
Jede Münze hat zwei Seiten.
Each coin has two sides.
- neuter (das Kind / the child = neuter)
Ein jedes Kind weint manchmal.
Jedes Kind weint manchmal.
Every child cries sometimes.
- male (der Baum / the tree = male)
Ein jeder Baum hat Wurzeln.
Jeder Baum hat Wurzeln.
Every tree has roots.
- generic (meaning everyone, all genders)
Hier ist ein jeder willkommen.
Hier ist jeder willkommen.
Everybody is welcome here.
But as said before: The version without article is always the version with the better style. So when you write or speak, better don't use that article. But when you read or hear it you should know that it is an allowed version.
You might read or hear the generic usage more often than the versions where you use it together with a noun. It rarely is used together with a noun as shown in my first three examples, so the chances are low that you will hear or read such a sentence.
This might only be worth the status of a comment, but I think it is relevant.
Maybe it is so that the "ein" in "ein jeder" isn't the indefinite article at all, but the count word?? E.g. we say in Swedish "var och en" (=every and one), where I don't believe that the "en" is an article, but a count word. In Swedish as in German the indefinite article is a homonyme with the count word for one, wherease they're different words in English. As a matter of fact, and what is easily overlooked, this "one" is also present in the English expression "everyone", which points to a possible common root of the expressions.