Given matches, find the number of topologically distinct planar arrangements which can be made. The first few values are 1, 1, 3, 5, 10, 19, 39, ... (Sloane's A003055).
See also Cigarettes, Matchstick Graph
References
Gardner, M. ``The Problem of the Six Matches.'' In The Unexpected Hanging and Other Mathematical Diversions.
Chicago, IL: Chicago University Press, pp. 79-81, 1991.
Sloane, N. J. A. Sequence
A003055/M2464
in ``An On-Line Version of the Encyclopedia of Integer Sequences.''
http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.
The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995.