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Number of isomorphism classes of 3-regular loopless multigraphs of order 2n.
9

%I #16 Mar 19 2020 14:15:13

%S 1,3,9,32,135,709,4637,38374,391473,4764778,66913591,1056886475,

%T 18446472265,351482430368,7247888726269,160671989129665,

%U 3808499268504548,96094161981827499,2570930535917564366,72688753062897675445

%N Number of isomorphism classes of 3-regular loopless multigraphs of order 2n.

%C Initial terms computed using software at http://users.cecs.anu.edu.au/~bdm/nauty/

%H L. Travis, <a href="http://arxiv.org/abs/math/9811127">Graphical Enumeration: A Species-Theoretic Approach</a>, arXiv:math/9811127 [math.CO], 1998.; Ph.D. thesis, Brandeis University, 1999, Section 4.3.

%F Euler transform of A000421.

%Y Column k=3 of A333330.

%Y Cf. A000421 (connected, inv. Eul. trans.), A129427, A129418, A129420, A129422, A129424, A129426.

%K nonn

%O 1,2

%A _Brendan McKay_, Apr 15 2007

%E a(13)-a(20) from _Andrew Howroyd_, Mar 19 2020