Novel - mathematics = ? : Making sense of The Housekeeper and Professor the

Is this a really smart and thoughtful novel, or a bit of dressed-up sentimental claptrap? I'm half-way through and holding off on judgment so far. Yoko Ogawa's "The Housekeeper and the Professor" is very simple in composition: 40ish single mom, Japan ca 1992, takes on a job as a housemaid to a math professor who's lost his long-term memory in a car accident; she brings her 10-year-old son, whom the prof dubs "Root," along with her to work and the three develop an unlikely bond over the twin subjects of math and baseball. Echoes here of the many mentor-themed books that have followed in the wake of the hugely successful Tuesdays with Morrie. Also, on the literary side, echoes of mentor novels such as The Reader and a slew of recent entries I haven't read - something about a French professor and the lessons he imparts? The relation among the 3 is sweet, but I don't see its point exactly other than as a vehicle; the professor posits various math problems to mom and son and teaches them about prime #s, perfect #s, and other mathematical oddities. Somehow, they're interested. Somehow, I'm not. If you purge this book of the mathematical quotient (novel - math = ?) what have you got? Ogawa, in the 2nd half, must make more of the relationships among the 3. One oddity (echo of Oliver Sacks?) is that the prof can retain only 80 minutes of memory, so each day it's as if he meets the housekeeper & son anew. This could be greatly developed for poignancy or even for drama, but it kind if just lies there as a given fact - the novel (the novelist?) is too polite to probe and prod it into life.