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%I #35 Jun 22 2018 20:46:16
%S 0,0,2,3,6,15,42,123,380,1212,3966,13265,45144,155955,545690,1930635,
%T 6897210,24852576,90237582,329896569,1213528736,4489041219,
%U 16690581534,62346895571,233893503330,880918093866,3329949535934
%N Number of self-avoiding polygons with perimeter n on hexagonal [ =triangular ] lattice.
%C The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.
%D B. D. Hughes, Random Walks and Random Environments, Oxford 1995, vol. 1, p. 459.
%H I. Jensen, <a href="/A036418/b036418.txt">Table of n, a(n) for n = 1..60</a>
%H Iwan Jensen, <a href="https://arxiv.org/abs/cond-mat/0409039">Self-avoiding walks and polygons on the triangular lattice</a>, arXiv:cond-mat/0409039 [cond-mat.stat-mech], 2004.
%H G. Nebe and N. J. A. Sloane, <a href="http://www.math.rwth-aachen.de/~Gabriele.Nebe/LATTICES/A2.html">Home page for hexagonal (or triangular) lattice A2</a>
%H <a href="/index/Aa#A2">Index entries for sequences related to A2 = hexagonal = triangular lattice</a>
%Y Cf. A001334, A284869.
%K nonn,walk
%O 1,3
%A _N. J. A. Sloane_