%I M2654 #27 Feb 11 2024 06:45:07
%S 1,3,7,15,31,62,122,235,448,842,1572,2904,5341,9743,17718,32009,57701,
%T 103445,185165,329904,587136,1040674,1843300,3253020,5738329,10090036,
%U 17736533,31086416,54484239,95220744,166451010,290209573
%N Site 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="/A006739/b006739.txt">Table of n, a(n) for n = 0..82</a> (from link below)
%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/20190419142006/https://researchers.ms.unimelb.edu.au/~ij@unimelb/dirperc/series/triasite_cs.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>
%K nonn
%O 0,2
%A _N. J. A. Sloane_, _Simon Plouffe_