A066863 Number of binary arrangements without adjacent 1's on n X n staggered hexagonal grid.

2, 6, 43, 557, 14432, 719469, 70372090, 13351521479, 4941545691252, 3559349503024593, 4993739972681894885, 13642580224488264353504, 72582736229683196932680697, 751993955499337790653321567382, 15172223086707160824288341875907978

Offset: 1

Author

R. H. Hardin, Jan 25 2002

Keywords

• nonn

Examples

			Neighbors for n=4:
o--o--o--o
| /|\ | /|
|/ | \|/ |
o--o--o--o
| /|\ | /|
|/ | \|/ |
o--o--o--o
| /|\ | /|
|/ | \|/ |
o--o--o--o
		

References

• Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 342-349.
• J. Katzenelson and R. P. Kurshan, S/R: A Language for Specifying Protocols and Other Coordinating Processes, pp. 286-292 in Proc. IEEE Conf. Comput. Comm., 1986.

Links

• Steven R. Finch, Hard Square Entropy Constant [Broken link]
• Steven R. Finch, Hard Square Entropy Constant [From the Wayback machine]
• Sean A. Irvine, Java program (github)
• Eric Weisstein's World of Mathematics, Hard Hexagon Entropy Constant

Crossrefs

Cf. A006506, A027683, A066864, A066865, A066866.

Extensions

More terms from Sean A. Irvine, Nov 15 2023