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%I M5343 #14 Mar 16 2018 20:12:09
%S 1,70,16800,9238320,9520156800,16305064776000,42856575521760000,
%T 163329351308323200000,864876880105205071104000,
%U 6155146233167046820024320000,57316399761348433188962519040000
%N Number of labeled trivalent (or cubic) 3-connected graphs with 2n nodes.
%D R. W. Robinson, personal communication.
%D R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1976.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H R. W. Robinson, <a href="/A007100/b007100.txt">Table of n, a(n) for n = 2..28</a>
%H R. W. Robinson, <a href="/A002829/a002829.pdf">Cubic labeled graphs, computer print-out, n.d.</a> (see last page)
%F a(n) = (2*n)!*r(n)/(3*n*2^n) where r(2) = 1 and r(n) = (3*n-2) * (r(n-1) + Sum_{i=2..n-2} r(i) * r(n-i)). - _Sean A. Irvine_, Oct 11 2017
%K nonn
%O 2,2
%A _N. J. A. Sloane_.
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