I just finished reading Yōko Ogawa's "The Housekeeper and the Professor". One of the main characters - "the professor" - is a retired mathematician who regularly takes part in contests published in a fictitious mathematical journal which awards small prizes for the best solutions to these problems. (There aren't any further details, but it seems they're looking for proofs for certain conjectures and the winning entries are later published.)
I know that there used to be a certain tradition of awarding prizes for mathematical problems ages ago, but I've never heard of mathematical journals with regular competitions like this (with or without prizes). Is this part of the story based on facts or did the author invent it? (FWIW, the story is set in the 1990s.)