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Search: id:A066866
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| A066866 |
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Number of binary arrangements without adjacent 1's in n X n rhombic hexagonal grid torus. |
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+0
13
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| 1, 5, 22, 201, 4216, 162314, 12329633, 1831137521, 528106112383, 296848246952000
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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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
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S. R. Finch, Hard Square Entropy Constant
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EXAMPLE
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neighbors for n=4:
.|/ |/ |/ |/
-o--o--o--o-
/| /| /| /|
.|/ |/ |/ |/
-o--o--o--o-
/| /| /| /|
.|/ |/ |/ |/
-o--o--o--o-
/| /| /| /|
.|/ |/ |/ |/
-o--o--o--o-
/| /| /| /|
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PROGRAM
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[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+1) mod N]`
+$[(i-1) mod N][j]` ))) end
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CROSSREFS
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Cf. A006506 A027683 A066863 A066864 A066865.
Adjacent sequences: A066863 A066864 A066865 this_sequence A066867 A066868 A066869
Sequence in context: A006294 A129437 A048252 this_sequence A115657 A066865 A005632
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KEYWORD
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nonn
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AUTHOR
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Ron Hardin rhh(AT)cadence.com Jan 25, 2002
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