%I A003055 M2464
%S A003055 1,1,3,5,10,19,39
%N A003055 Number of connected graphs, up to homeomorphism, that can be drawn in 
               the plane using unit-length edges.
%C A003055 K_4 can't be so drawn even though it is planar. Although a square with 
               a tail of length 1 and a triangle with a tail of length 2 are nonisomorphic 
               graphs with five edges, they are homeomorphic as topological spaces.
%D A003055 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A003055 M. Gardner, The Unexpected Hanging and Other Mathematical Diversions. 
               Simon and Schuster, NY, 1969, p. 80.
%H A003055 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               MatchProblem.html">Link to a section of The World of Mathematics.</
               a>
%Y A003055 Cf. A066951.
%Y A003055 Sequence in context: A133999 A014610 A117591 this_sequence A018101 A158568 
               A068013
%Y A003055 Adjacent sequences: A003052 A003053 A003054 this_sequence A003056 A003057 
               A003058
%K A003055 nonn,more,nice
%O A003055 1,3
%A A003055 N. J. A. Sloane (njas(AT)research.att.com).
%E A003055 Corrected by Brendan McKay (bdm(AT)cs.anu.edu.au) and Les Reid (les(AT)math.smsu.edu), 
               May 25, 2002