A005966 Number of trivalent planar loopless multigraphs with 2n nodes.
1, 2, 5, 17, 71, 357, 2143, 14960, 116560, 986983, 8874072
Offset: 1
References
- A. T. Balaban, Enumeration of Cyclic Graphs, pp. 63-105 of A. T. Balaban, ed., Chemical Applications of Graph Theory, Ac. Press, 1976; see p. 92.
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Programs
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nauty
for n in {1..10}; do geng -cqD3 $[2*$n] | planarg -q | multig -ur3; done # Sean A. Irvine, Oct 25 2016
Extensions
a(7)-a(11) and title improved by Sean A. Irvine, Oct 25 2016