Philipp <p.stephani2@gmail.com> schrieb am Do., 20. Juli 2017 um 23:32 Uhr:

>
> The docstring of `print-gensym' says:
>
>    When the uninterned symbol appears within a recursive data structure,
>    and the symbol appears more than once, in addition use the #N# and #N=
>    constructs as needed, so that multiple references to the same symbol are
>    shared once again when the text is read back.
>

OK, so you could read this as "the numbering is only used for recursive
data structures". But I don't understand why; it seems equally appropriate
for non-recursive data structures.