|
| |
|
|
A066864
|
|
Number of binary arrangements without adjacent 1's on n X n rhombic hexagonal grid.
|
|
12
| |
|
|
2, 6, 42, 524, 13322, 647252, 61758332, 11435477118, 4129523869606, 2902264461628298, 3973109800760143708
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
REFERENCES
| S. 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
| S. R. Finch, Hard Square Entropy Constant
|
|
|
EXAMPLE
| Neighbors for n=4:
o--o--o--o
| /| /| /|
|/ |/ |/ |
o--o--o--o
| /| /| /|
|/ |/ |/ |
o--o--o--o
| /| /| /|
|/ |/ |/ |
o--o--o--o
|
|
|
PROG
| [S/R] proc a
stvar $[N][N]:boolean
init $[][] := false
cyset true
asgn $[][]->{false, true}
kill +[i in 0.. N-1](
+[j in 0.. N-1](
$[i][j]`*(
($[i][j+1]`?(j<=N-2)|false)
+($[i-1][j+1]`?((i>0)*(j<=N-2))|false)
+($[i-1][j]`?(i>0)|false) ))) end
|
|
|
CROSSREFS
| Cf. A006506 A027683 A066863 A066865 A066866.
Sequence in context: A161632 A115974 A179330 * A181737 A116896 A061062
Adjacent sequences: A066861 A066862 A066863 * A066865 A066866 A066867
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| R. H. Hardin (rhhardin(AT)att.net), Jan 25, 2002
|
| |
|
|
