Triplets within triplets

[stoat_king]

I hope this isn't too stupid a question:

I love triplets. But I never never seen any sheet music where one triplet has itself been divided into triplets - ie a ninth of a note.
I'm just curious if any of you more knowledgeable people have ever seen such a thing?

In context, I am practising improvising with a number of jazz standards.
To simplify things, I'm just playing a fairly steady beat in the left hand.
With the right hand, I am experimenting with the rhythm.
Both two and four notes to the beat sounds fine. Triplets are great.
Five notes to the beat is nice in small amounts.
What about nine?
Specifically, taking one of the constituent 1/3 note parts of the triplet and dividing that into triplets. Like this.

1/3 note | 1/3 note | 1/3 note
=>
1/9 note | 1/9 note | 1/9 note | 1/3 note | 1/3 note 

It sounds ok. Im not sure its worth the hassle, but I love my maths so I was bound to try.
However, it has piqued by curiosity. I have read a ton of sheet music and NEVER seen this.
Have you?

[listesso_tempo]

Yes, nested tuplets, not necessarily triplets inside triplets, are actually quite common in newer music. I've encountered some in Rachmaninoff's 3rd Piano Concerto too quite recently, i.e. right after piu vivo marking in the Intermezzo (Page 37 on Boosey&Hawkes edition).