Re: [math-fun] OEIS: conjecture about certain forests and their exponential generating functions

I wrote:

Looks OK to me. I did a quick search and found this, which states and explains a nice general principle of which the above is a very special case.

http://math.berkeley.edu/~mhaiman/math172.../exponential.pdf

In particular, look at the section called "The function composition principle".

Oops. http://math.berkeley.edu/~mhaiman/math172-spring10/exponential.pdf (Thanks to Charles Greathouse for pointing out that I screwed up the link. No thanks to Google for making it painful to get the original URL for a link found by their search.) -- g