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Search: id:A085576
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| A085576 |
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Array read by antidiagonals: T(n,k) = size of maximal subset of nodes in n X k grid such that there at least 3 edges between any pair of nodes (n >= 1, k >= 1). |
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+0
2
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| 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 2, 3, 3, 4, 4, 4, 3, 3, 3, 4, 4, 5, 5, 4, 4, 3, 3, 4, 5, 6, 6, 6, 5, 4, 3, 4, 5, 6, 6, 7, 7, 6, 6, 5, 4, 4, 5, 6, 8, 8, 8, 8, 8, 6, 5, 4, 4, 6, 7, 8, 9, 9, 9, 9, 8, 7, 6, 4
(list; table; graph; listen)
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OFFSET
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1,7
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COMMENT
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The 1-neighborhoods of the nodes must be disjoint: i.e. this is a 1-error correcting code.
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FORMULA
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T(n, 1) = floor((n+2)/3), T(n, 2) = floor((n+1)/2).
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EXAMPLE
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Array begins
1 1 1 2 2 2 3 3 3 4 ...
1 1 2 2 3 3 4 4 5 5 ...
1 2 2 3 4 4 5 6 6 7 ...
2 2 3 4 5 6 6 8 8 9 ...
For example, T(3,4) = 3 (*'s indicate the chosen nodes):
o--*--o--o
|..|..|..|
o--o--o--o
|..|..|..|
*--o--o--*
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CROSSREFS
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Main diagonal gives A085577.
Sequence in context: A032550 A109399 A036450 this_sequence A108622 A112348 A127321
Adjacent sequences: A085573 A085574 A085575 this_sequence A085577 A085578 A085579
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KEYWORD
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nonn,tabl
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jul 08 2003
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