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 2^{n} - 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.

Can someone point me to this paper?

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.

something like "What does f(n) count?". It also could have been "What's f(n) the number of?" or something like that. – Hans Stricker Sep 13 '10 at 7:24