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Search: id:A135942
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| A135942 |
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Number of n-celled polyominoes with perimeter < 2n+2. |
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+0
1
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| 0, 0, 0, 1, 1, 8, 25, 114, 438, 1826, 7339, 29876, 120346
(list; graph; listen)
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OFFSET
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1,6
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COMMENT
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These are n-cell polyominoes with the perimeter less than the maximum possible one.
If we associate a graph to a polyomino with vertices representing cells and edges representing two cells with a common edge, then this sequence enumerates polyominoes whose corresponding graphs have cycles.
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FORMULA
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A000105(n)-A131482(n)
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CROSSREFS
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Sequence in context: A042637 A133661 A139026 this_sequence A068315 A069586 A042189
Adjacent sequences: A135939 A135940 A135941 this_sequence A135943 A135944 A135945
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KEYWORD
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hard,more,nonn
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AUTHOR
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Tanya Khovanova (tanyakh(AT)yahoo.com), Mar 03 2008
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