%I A002851 M1521 N0595
%S A002851 1,2,5,19,85,509,4060,41301,510489,7319447,117940535,2094480864,
%T A002851 40497138011,845480228069,18941522184590,453090162062723,
%U A002851 11523392072541432,310467244165539782,8832736318937756165
%N A002851 Number of unlabeled trivalent (or cubic) connected graphs with 2n nodes.
%D A002851 CRC Handbook of Combinatorial Designs, 1996, p. 647.
%D A002851 H. Gropp, Enumeration of regular graphs 100 years ago, Discrete Math., 
               101 (1992), 73-85.
%D A002851 F. Harary, Graph Theory. Addison-Wesley, Reading, MA, 1969, p. 195.
%D A002851 R. C. Read, Some applications of computers in graph theory, in L. W. 
               Beineke and R. J. Wilson, editors, Selected Topics in Graph Theory, 
               Academic Press, NY, 1978, pp. 417-444.
%D A002851 R. C. Read and G. F. Royle, Chromatic roots of families of graphs, pp. 
               1009-1029 of Y. Alavi et al., eds., Graph Theory, Combinatorics and 
               Applications. Wiley, NY, 2 vols., 1991.
%D A002851 R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
%D A002851 R. W. Robinson and N. C. Wormald, Numbers of cubic graphs. J. Graph Theory 
               7 (1983), no. 4, 463-467.
%D A002851 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A002851 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%H A002851 M. Klin, M. R\"ucker, Ch. R\"ucker and G. Tinhofer, <a href="http://www-lit.ma.tum.de/
               veroeff/html/950.05003.html">Algebraic Combinatorics</a>
%H A002851 M. Meringer, <a href="http://www.mathe2.uni-bayreuth.de/markus/reggraphs.html">
               Tables of Regular Graphs</a>
%H A002851 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               CubicGraph.html">Cubic Graph</a>
%e A002851 a(0)=1 by convention.
%e A002851 a(1)=0 because there are no simple connected cubic graphs with 2 nodes.
%e A002851 a(2)=1 because the tetrahedron is the only cubic graph with 4 nodes.
%Y A002851 Cf. A005638, A032355.
%Y A002851 Connected regular graphs of degree k: A002851 (k=3), A006820 (k=4), A006821 
               (k=5), A006822 (k=6), A014377 (k=7), A014378 (k=8), A014381 (k=9), 
               A014382 (k=10), A014384 (k=11).
%Y A002851 Sequence in context: A138911 A107377 A058132 this_sequence A124348 A052324 
               A020115
%Y A002851 Adjacent sequences: A002848 A002849 A002850 this_sequence A002852 A002853 
               A002854
%K A002851 nonn,nice
%O A002851 2,2
%A A002851 N. J. A. Sloane (njas(AT)research.att.com).
%E A002851 More terms from R. C. Read (rcread(AT)math.uwaterloo.ca).