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Number of unlabeled hexagonal 2-trees with n hexagons.
2

%I #9 Feb 02 2021 19:33:28

%S 1,1,1,4,16,103,799,7286,71094,729974,7743818,84307887,937002302,

%T 10595117272,121568251909,1412555701804,16594126114458,

%U 196829590326284,2354703777373055,28385225424840078,344524656398655124,4207569734885041198,51674558137433627724

%N Number of unlabeled hexagonal 2-trees with n hexagons.

%H Andrew Howroyd, <a href="/A094637/b094637.txt">Table of n, a(n) for n = 0..200</a>

%H G. Labelle, C. Lamathe and P. Leroux, <a href="http://arXiv.org/abs/math.CO/0312424">Labeled and unlabeled enumeration of k-gonal 2-trees</a>, arXiv:math/0312424 [math.CO], Dec 23 2003.

%Y Column k=6 of A340811.

%Y Cf. A054581.

%K nonn

%O 0,4

%A _Vladeta Jovovic_, Jun 06 2004

%E Terms a(21) and beyond from _Andrew Howroyd_, Feb 02 2021