Paul ponders to his therapist that he might call his dream formula Buchman's Last Formula. This is clearly inspired by the famous Fermat's Last Theorem, perhaps the most famous mathematical mystery in history. Pierre de Fermat scribbled a note in the margin of a book he'd been reading that he had found this "truly marvelous proof" but the margin was too small. He unfortunately died without providing this proof, leaving the world to ponder this mystery for centuries.
Although the proof has been confirmed by modern mathematicians using contemporary methods, there is a strong belief that Fermat's proof had to have been more elegant and simple. Fermat's proof was lost in the fabric of time; Paul's dream-formula got lost in the fabric of his dry cleaning sadly.