%I M1788 #17 Oct 02 2018 11:15:18
%S 1,2,7,32,168,970,5984,38786,261160,1812630,12895360,93638634,
%T 691793872,5186869122,39388514522,302457399674,2345362579172,
%U 18345337742960,144612959167806,1147920496989270,9169516892088470
%N Number of polygons of length 4n on Manhattan lattice.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H D. Bennett-Wood, J. L. Cardy, I. Enting, A. J. Guttmann and A. L. Owczarek, <a href="https://arxiv.org/abs/cond-mat/9805146">On the Non-Universality of a Critical Exponent for Self-Avoiding Walks</a>, arXiv:cond-mat/9805146 [cond-mat.stat-mech], 1998; Nuc. Phys. B, 528, 533--552, 1998. [From Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 13 2010]
%H I. G. Enting and A. J. Guttmann, <a href="http://www.cmar.csiro.au/e-print/internal/enting_x1985e.pdf">Self-avoiding polygons on the square, L and Manhattan lattices</a>, J. Phys. A 18 (1985), 1007-1017.
%K nonn,walk,nice
%O 1,2
%A _N. J. A. Sloane_
%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 13 2010