%I A006729 M2088
%S A006729 2,16,72,252,764,2094,5362,12968,30138,67446,147048,311940,
%T A006729 649860,1325234,2668130,5278066,10346200,19977010,38329556,
%U A006729 72546986,136785444,254596418,473093498,868060738,1593517724
%N A006729 Series for second parallel moment of square lattice (eventually changes 
               sign).
%D A006729 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006729 J. W. Essam, A. J. Guttmann and K. De'Bell, On two-dimensional directed 
               percolation, J. Phys. A 21 (1988), 3815-3832.
%D A006729 Jensen, Iwan; Guttmann, Anthony J.; Series expansions of the percolation 
               probability for directed square and honeycomb lattices. J. Phys. 
               A 28 (1995), no. 17, 4813-4833.
%H A006729 I. Jensen, <a href="b006729.txt">Table of n, a(n) for n = 0..170</a> 
               (from link below)
%H A006729 I. G. Enting, A, J. Guttmann and I. Jensen, <a href="http://arXiv.org/
               abs/hep-lat/?9410005">Low-Temperature Series Expansions for the Spin-1 
               Ising Model</a>, J. Phys. A. 27 (1994) 6987-7006.
%H A006729 I. Jensen, <a href="http://www.ms.unimelb.edu.au/~iwan/dirperc/series/
               sqbt2.ser">More terms</a>
%Y A006729 Cf. A006461, A006727, A006728, A006730.
%Y A006729 Sequence in context: A034579 A006733 A034580 this_sequence A007758 A034581 
               A028336
%Y A006729 Adjacent sequences: A006726 A006727 A006728 this_sequence A006730 A006731 
               A006732
%K A006729 nonn
%O A006729 0,1
%A A006729 N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
%E A006729 The first negative term is the 70th.