I am desperately searching for a paper I once have read, but cannot find anymore. It was about a counting function f(n) - the only thing I remember is that f's expression contained n! and 2n - and the question in the title was something like "What does f(n) count?". The paper compared three or so different approaches, and was written as a trialog.



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If you know about other papers on this question - "What does f(n) count?", with f(n) any counting-but-what function, I'd be happy to learn about them. 



"What does f(n) count?" - in search for a paper
Could it be [*The answer is $2^n·n$! What's the question?*](http://dx.doi.org/10.2307/2589493) by Gary Gordon (Amer. Math. Monthly **106** (1999), no. 7, 636–645)?


