A173413 Number of imperfect staircase polygons counted by half-perimeter.

1, 6, 29, 130, 561, 2368, 9855, 40622, 166303, 677420, 2748952, 11122504, 44898891, 180912196, 727866627, 2924860426, 11741400147, 47094376488, 188760540056, 756125505044, 3027303565311, 12115171905092, 48466474069668

Offset

4,2

Comments

Generating function is the solution of a Fuchsian ODE of order 8.

References

A. R. Conway, A. J. Guttmann and M. Delest, The number of three-choice polygons, Mathl. Comput. Modelling, 26 (1997), 51-58.

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).

Links

Table of n, a(n) for n=4..26.

Crossrefs

Sequence in context: A054146 A172062 A081674 * A008549 A345031 A351146

Adjacent sequences: A173410 A173411 A173412 * A173414 A173415 A173416

Keyword

nonn

Author

Iwan Jensen (I.Jensen(AT)ms.unimelb.edu.au), Feb 17 2010

Status

approved