# [Jelly], 16 [bytes]

    :2ạḶgþ`«2ị“* @”Y

[Try it online!]

### How it works

    :2ạḶgþ`«2ị“* @”Y  Main link. Argument: 2n + 1

    :2                Perform integer division by 2, yielding n.
       Ḷ              Yield [0, ..., 2n].
     ạ                Take the absolute difference of the result to both sides.
                      This yields A := [n, ... 0, ... n].
          `           Call the quicklink to the left with left and right argument A.
         þ              Table; call the link to the left for all x in A and all y in A.
        g                 Yield the GCD of x and y.
           «2         Truncate the GCD at 2, leaving 0 for the origin, 1 for coprime
                      coordinates, and 2 otherwise.
             ị“* @”   Index into that string, mapping [1, 2, 0] to ['*', ' ', '@'].
                   Y  Join, separating by linefeeds.

[bytes]: https://github.com/DennisMitchell/jelly/wiki/Code-page
[Jelly]: https://github.com/DennisMitchell/jelly
[Try it online!]: http://jelly.tryitonline.net/#code=OjLhuqHhuLZnw75gwqsy4buL4oCcKiBA4oCdWQ&input=&args=Nw