I'm not aware of any, but maybe somebody else is. A more general question is are there any other DFW-ish math-ish writings to be found? Against The Day (Pynchon) is not really math-ish, but it does have a good bit of math (more than GR at least), and a DFW fan would probably like it. Stella Maris (McCarthy) is perhaps neither DFW-ish nor math-ish, but it is Serious Fiction centered on a mathematician and is probably the best work of fiction to feature Alexander Grothendieck. I have heard that Solenoid (Cartarescu) has some math in it, though I fear it's still sitting on my shelf. Every Arc Bends Its Radian (due in a couple months from Sergio De La Pava) has a math-ish title but I doubt it will actually contain much math.

Michael Harris -- a mathematician who wrote a review of the DFW Infinity book -- has a book called "Mathematics Without Apologies", which I liked, though it's non-fiction. There is also "Birth of a Theorem" by Fields medalist Cedric Villani which is an interesting read -- not fiction, but it is experimental in many respects and I would say worth a read.

You'll probably enjoy When We Cease to Understand the World by Benjamin Labatut.

Oh, good idea! I read The Maniac but not that one, and the former should be on my list too.

Awesome recommendation, I enjoyed that one very much!

Endnote 123 in Infinite Jest