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Search: id:A057818
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| A057818 |
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Number of factorable (see A057765 for definition) subsets of a 2 X n uniform grid. |
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+0
1
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| 0, 1, 6, 33, 108, 345, 1014, 2865, 7464, 19791, 51286, 133249
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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There are six factorable subsets of
[___] namely [11_] [1_1] [_11] [111] [_11] [11_]
[___] ...... [22_] [2_2] [_22] [222] [22_] [_22], so a(3) = 6
(the numerals denote the elements of a particular translated copy).
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CROSSREFS
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See A057765 and A057750.
Sequence in context: A069065 A073343 A135526 this_sequence A063267 A082106 A073375
Adjacent sequences: A057815 A057816 A057817 this_sequence A057819 A057820 A057821
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KEYWORD
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nonn,nice,more
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AUTHOR
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John W. Layman (layman(AT)math.vt.edu), Nov 07 2000
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