I'd love to be able generate dates dynamically using the {{{n}}} org macro,
or some other mechanism.  I don't immediately see how that would be
possible but maybe someone can guide me.  I'd want to do something
equivalent to this pseudo-elisp:

(let ((base-date 2017-09-05))
  (+ base-date (* 7 {{{n}}}))

I haven't looked into how date objects are parsed in org-mode, though, so I
have no idea how hard it would be to actually implement something like
this.

Thank you everyone!