I feel ashamed answering after more than two days, but I never notice when people answer to me on HN. Anyway, you can find a description of the puzzle on Wikipe

I feel ashamed answering after more than two days, but I never notice when people answer to me on HN. Anyway, you can find a description of the puzzle on Wikipedia [1]. It is almost 50 years old! [1] https://en.m.wikipedia.org/wiki/Sum_and_Product_Puzzle https://en.m.wikipedia.org/wiki/Sum_and_Product_Puzzle