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A173413 Number of imperfect staircase polygons counted by half-perimeter. 0
1, 6, 29, 130, 561, 2368, 9855, 40622, 166303, 677420, 2748952, 11122504, 44898891, 180912196, 727866627, 2924860426, 11741400147, 47094376488, 188760540056, 756125505044, 3027303565311, 12115171905092, 48466474069668 (list; graph; refs; listen; history; text; internal format)
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 A026675 A026873

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

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Last modified October 21 21:45 EDT 2018. Contains 316429 sequences. (Running on oeis4.)