|Journal of Integer Sequences, Vol. 6 (2003), Article 03.4.7|
Abstract: Lajos Takács gave a somewhat formidable alternating sum expression for the number of forests of unrooted trees on n labeled vertices. Here we use a weight-reversing involution on suitable tree configurations to give a combinatorial derivation of Takács' result.
(Concerned with sequence A001858 .)
Received October 3, 2003; revised version received November 3, 2003. Published in Journal of Integer Sequences January 15, 2004.