BALTIC-WAY 2022 Problem 7
The writer Arthur has co-authors who write books with him. Each book has a list of authors including Arthur himself. No two books have the same set of authors. At a party with all his co-author, each co-author writes on a note how many books they remember having written with Arthur. Inspecting the numbers on the notes, they discover that the numbers written down are the first Fibonacci numbers (defined by and ). For which is it possible that none of the co-authors had a lapse of memory?
Dataset text AI-MO AoPS. Quoted with source.
Solutions
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