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%I M1511 #14 Oct 25 2016 14:26:47
%S 1,2,5,17,71,357,2143,14960,116560,986983,8874072
%N Number of trivalent planar loopless multigraphs with 2n nodes.
%D 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.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%o (nauty/bash) for n in {1..10}; do geng -cqD3 $[2*$n] | planarg -q | multig -ur3; done # _Sean A. Irvine_, Oct 25 2016
%Y Cf. A000421 (allowing non-planar), A005957 (allowing loops).
%K nonn,more
%O 1,2
%A _N. J. A. Sloane_.
%E a(7)-a(11) and title improved by _Sean A. Irvine_, Oct 25 2016