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Search: id:A145815
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| A145815 |
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1/4 of the number of islands of ones fitting in an n X n array symmetric about the diagonal and under 90 degree rotation with all ones connected only either three adjacent vertically or three adjacent horizontally. |
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+0
1
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| 0, 0, 0, 0, 1, 0, 1, 0, 3, 2, 4, 4, 6, 4, 7, 6, 10, 8, 12, 12, 15, 14, 19, 16, 22, 20, 26, 24, 31, 28
(list; graph; listen)
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OFFSET
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1,9
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EXAMPLE
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9 X 9 example with 12 islands
.0.1.1.1.0.1.1.1.0
.1.0.0.0.0.0.0.0.1
.1.0.0.1.1.1.0.0.1
.1.0.1.0.0.0.1.0.1
.0.0.1.0.0.0.1.0.0
.1.0.1.0.0.0.1.0.1
.1.0.0.1.1.1.0.0.1
.1.0.0.0.0.0.0.0.1
.0.1.1.1.0.1.1.1.0
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CROSSREFS
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Sequence in context: A154392 A069745 A112199 this_sequence A059851 A047993 A033177
Adjacent sequences: A145812 A145813 A145814 this_sequence A145816 A145817 A145818
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KEYWORD
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nonn
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AUTHOR
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Ron Hardin (rhhardin(AT)att.net), Oct 20 2008
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