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%I M2232 #24 Feb 11 2024 06:44:53
%S 1,0,0,-1,0,-3,1,-9,6,-29,27,-99,112,-351,450,-1275,1782,-4704,6998,
%T -17531,27324,-65758,106211,-247669,411291,-935107,1587391,-3535398,
%U 6108103,-13373929,23438144,-50592067,89703467,-191306745,342473589
%N Percolation series for hexagonal 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 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H I. Jensen, <a href="/A006803/b006803.txt">Table of n, a(n) for n = 0..51</a>
%H J. Blease, <a href="https://doi.org/10.1088/0022-3719/10/7/003">Series expansions for the directed-bond percolation problem</a>, J. Phys C vol 10 no 7 (1977), 917-924.
%H J. W. Essam, A. J. Guttmann and K. De'Bell, <a href="https://doi.org/10.1088/0305-4470/21/19/018">On two-dimensional directed percolation</a>, J. Phys. A 21 (1988), 3815-3832.
%H I. Jensen, <a href="https://web.archive.org/web/20190419141853/https://researchers.ms.unimelb.edu.au/~ij@unimelb/dirperc/series/triabond_pp.ser">More terms</a>
%H Iwan Jensen and Anthony J. Guttmann, <a href="https://arxiv.org/abs/cond-mat/9509121">Series expansions of the percolation probability for directed square and honeycomb lattices</a>, arXiv:cond-mat/9509121, 1995; J. Phys. A 28 (1995), no. 17, 4813-4833.
%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>
%Y Cf. A006809.
%K sign
%O 0,6
%A _N. J. A. Sloane_