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A066865
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Number of binary arrangements without adjacent 1's on n X n staggered hexagonal torus bent for odd n.
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4
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1, 5, 22, 217, 4726, 164258, 14840533, 1834600977, 669877863205, 296979228487760, 434542100979981567
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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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.
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LINKS
| S. R. Finch, Hard Square Entropy Constant
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EXAMPLE
| Neighbors for n=4: (The dots here represent spaces)
\|/ | \|/ |
-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
/| /|\ | /|\ |\
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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]`*(
(
$[i][(j-1) mod N]`
+$[(i-1) mod N][j]`
+(
$[(i-1) mod N][(j-1) mod N]`
? ((j mod 2)=0) |
$[(i+1) mod N][(j-1) mod N]`
)
) ? ((j>0)+((N mod 2)=0)) | (
$[(i-1) mod N][j]`
+$[(i-1) mod N][(j-1) mod N]`
+$[(i+1) mod N][(j-1) mod N]` )))) end
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CROSSREFS
| Cf. A006506 A027683 A066863 A066864 A066866, shifted instead of bent A067967.
Row sums of A067015.
Sequence in context: A048252 A066866 A115657 * A183902 A005632 A183408
Adjacent sequences: A066862 A066863 A066864 * A066866 A066867 A066868
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KEYWORD
| nonn
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AUTHOR
| R. H. Hardin (rhhardin(AT)att.net), Jan 25, 2002
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