%I #1 Jun 01 2010 03:00:00
%S 1,6,29,130,561,2368,9855,40622,166303,677420,2748952,11122504,
%T 44898891,180912196,727866627,2924860426,11741400147,47094376488,
%U 188760540056,756125505044,3027303565311,12115171905092,48466474069668
%N Number of imperfect staircase polygons counted by half-perimeter.
%C Generating function is the solution of a Fuchsian ODE of order 8.
%D A. R. Conway, A. J. Guttmann and M. Delest, The number of three-choice polygons, Mathl. Comput. Modelling, 26 (1997), 51-58.
%D A. J. Guttmann and I. Jensen, Fuchsian differential equation for the perimeter generating function of three-choice polygons, Sem. Lothar. Combin., 54 (2006), B54c (14pp).
%K nonn
%O 4,2
%A Iwan Jensen (I.Jensen(AT)ms.unimelb.edu.au), Feb 17 2010