%I M1055 #20 Oct 04 2019 07:39:58
%S 1,2,4,7,12,20,33,53,85,133,210,322,505,759,1192,1748,2782,3931,6476,
%T 8579,15216,17847,36761,33612,93961,47282,262987,-16105,827382,
%U -571524,2936705,-3661626,11507775,-18880652,48169220,-90436605
%N Site percolation series for square 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="/A006731/b006731.txt">Table of n, a(n) for n = 0..158</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 Iwan Jensen, <a href="https://researchers.ms.unimelb.edu.au/~ij@unimelb/dirperc/series/sqscs.ser">More terms</a>
%H Iwan Jensen, 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.
%Y Cf. A056532.
%K sign
%O 0,2
%A _N. J. A. Sloane_, _Simon Plouffe_