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Search: id:A143823
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| A143823 |
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Number of subsets {x(1),x(2),...,x(k)} of {1,2,...,n} such that all differences |x(i)-x(j)| are distinct. |
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+0
2
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| 2, 4, 7, 13, 22, 36, 57, 91, 140, 216, 317, 463, 668, 962, 1359, 1919, 2666, 3694, 5035, 6845
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OFFSET
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1,1
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COMMENT
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See A143824 for sizes of the largest subsets of {1,2,...,n} with the desired property.
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EXAMPLE
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{1,2,4} is a subset of {1,2,3,4}, with distinct differences 2-1=1, 4-1=3, 4-2=2 between pairs of elements, so {1,2,4} is counted as one of the 13 subsets of {1,2,3,4} with the desired property.
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CROSSREFS
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A143824
Sequence in context: A061257 A061255 A088111 this_sequence A119983 A151897 A085489
Adjacent sequences: A143820 A143821 A143822 this_sequence A143824 A143825 A143826
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KEYWORD
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nonn
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AUTHOR
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John W. Layman (layman(AT)math.vt.edu), Sep 02 2008
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