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%I #19 Sep 12 2019 14:22:11
%S 2,4,10,28,84,272,946,3486,13560,55432,236852,1054928,4881972,
%T 23420436,116204016,595246848,3142169416,17068245184,95267426432,
%U 545732236936,3204607199704
%N Number of independent vertex sets and vertex covers in the n-triangular honeycomb queen graph.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/IndependentVertexSet.html">Independent Vertex Set</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/VertexCover.html">Vertex Cover</a>
%F From _Andrew Howroyd_, Sep 12 2019: (Start)
%F a(n) = 6*A283117(n) - 2*A326611(n) - 3*2^ceiling(n/2).
%F a(n) = 1 + Sum_{k>=1} A193986(n,k).
%F (End)
%Y Cf. A193986, A283117, A289883, A289893, A326611.
%K nonn,more
%O 1,1
%A _Eric W. Weisstein_, Jul 14 2017
%E a(13)-a(21) from _Andrew Howroyd_, Sep 12 2019
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