A067967 Number of binary arrangements without adjacent 1's on n X n hexagonal staggered torus shifted for odd n.

1, 5, 19, 217, 4076, 164258, 12285477, 1834600977, 527717587843, 296979228487760, 324881629286870822, 692625866382651263578, 2874716493700380888930840, 23237986479606982160703729647, 365788614113216462103977935612524, 11213018647250714014261414954480048385

Offset

1,2

References

Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 342-349.

Links

Table of n, a(n) for n=1..16.

Steven R. Finch, Hard Square Entropy Constant [Broken link]

Steven R. Finch, Hard Square Entropy Constant [From the Wayback machine]

Example

Neighbors for n=4:
:\|/ | \|/ |
:-o--o--o--o-
: | /|\ | /|\
:\|/ | \|/ |
:-o--o--o--o-
: | /|\ | /|\
:\|/ | \|/ |
:-o--o--o--o-
: | /|\ | /|\
:\|/ | \|/ |
:-o--o--o--o-
: | /|\ | /|\
Neighbors for n=5:
:\|/ | \|/ | \|
:-o--o--o--o--o-
: | /|\ | /|\ |\
:\|/ | \|/ | \|
:-o--o--o--o--o-
: | /|\ | /|\ |\
:\|/ | \|/ | \|
:-o--o--o--o--o-
: | /|\ | /|\ |\
:\|/ | \|/ | \|
:-o--o--o--o--o-
: | /|\ | /|\ |\
:\|/ | \|/ | \|
:-o--o--o--o--o-
: | /|\ | /|\ |\

Crossrefs

For bent instead of shifted for odd n see A066865.

Sequence in context: A058765 A317340 A328716 * A362281 A092751 A357363

Adjacent sequences: A067964 A067965 A067966 * A067968 A067969 A067970

Keyword

nonn

Author

R. H. Hardin, Feb 02 2002

Extensions

More terms from Sean A. Irvine, Nov 18 2023

Status

approved