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Math Never Seen

Why have certain mathematical symbols and notations gained general acceptance while others fell into oblivion? To answer this question I present quality criteria for mathematical symbols. I show many unknown, littleknown or little-used notations, some of which deserve much wider use. I also show some new symbols and some ideas for new notations, especially for some well-known concepts which lack a good notation (Stirling numbers, greatest common divisor and least common multiple).