A145157 Number of Greek-key tours on an n X n board; i.e., self-avoiding walks on n X n grid starting in top left corner.

1, 2, 8, 52, 824, 22144, 1510446, 180160012, 54986690944, 29805993260994, 41433610713353366, 103271401574007978038, 660340630211753942588170, 7618229614763015717175450784, 225419381425094248494363948728158

Offset

1,2

Comments

The sequence may be enumerated using standard methods for counting Hamiltonian cycles on a modified graph with two additional nodes, one joined to a corner vertex and the other joined to all other vertices. - Andrew Howroyd, Nov 08 2015

Links

Table of n, a(n) for n=1..15.

Nathaniel Johnston, On Maximal Self-Avoiding Walks

Ville H. Pettersson, Enumerating Hamiltonian Cycles, The Electronic Journal of Combinatorics, Volume 21, Issue 4, 2014.

Crossrefs

Cf. A046994, A046995, A145156, A160240, A160241.

Cf. A000532, A001184, A120443, A003763, A271507, A007764.

Sequence in context: A057629 A191507 A191602 * A323871 A183945 A193651

Adjacent sequences: A145154 A145155 A145156 * A145158 A145159 A145160

Keyword

hard,nonn,walk

Author

Nathaniel Johnston, Oct 03 2008

Extensions

a(9)-a(15) from Andrew Howroyd, Nov 08 2015

Status

approved