login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A160240 Number of Greek-Key Tours on a 6 X n grid. 1
1, 6, 78, 469, 3501, 22144, 144476, 899432, 5585508, 34092855, 206571444, 1241016042, 7407467656, 43975776229, 259779839242, 1528563721468, 8960651209082, 52368047294410, 305173796833144, 1774059940879290, 10289839706255591, 59564855651625602, 344177608427972004, 1985502681113986836, 11437008315770485918, 65791536638478271291, 377999748832914166324, 2169320756101096085597, 12436728915873118081588, 71232070407411735554025 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Greek Key Tours are self-avoiding walks that touch every vertex of the grid and start at the bottom-left corner.

The sequence may be enumerated using standard methods for counting Hamilton 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 07 2015

LINKS

Table of n, a(n) for n=1..30.

N. Johnston, On Maximal Self-Avoiding Walks.

CROSSREFS

Cf. A046994, A046995, A145156, A145157.

Sequence in context: A167498 A250388 A231248 * A069669 A145359 A145360

Adjacent sequences:  A160237 A160238 A160239 * A160241 A160242 A160243

KEYWORD

nonn

AUTHOR

Nathaniel Johnston, May 05 2009

EXTENSIONS

a(11)-a(30) from Andrew Howroyd, Nov 07 2015

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 16 19:22 EDT 2018. Contains 316271 sequences. (Running on oeis4.)