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Search: id:A055659
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| A055659 |
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Number of (2,n)-partitions of a chain of length n^3. |
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+0
1
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| 0, 15, 253, 1653, 6786, 21115, 54615, 123753, 253828, 481671, 858705, 1454365, 2359878, 3692403, 5599531, 8264145, 11909640, 16805503, 23273253, 31692741, 42508810, 56238315, 73477503, 94909753, 121313676, 153571575, 192678265
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OFFSET
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1,2
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COMMENT
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a (k,n)-partition of a chain C is a chain of k intervals of C of length n
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FORMULA
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a(n)= (1/2) *(n-1)*(n^2+n-1)*(n^3-2*n+2)
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EXAMPLE
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a(2)=15 because in the linearly ordered set {1,..,8} we can choose in 15 ways 2 successive blocks of 2 consecutive elements
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CROSSREFS
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Adjacent sequences: A055656 A055657 A055658 this_sequence A055660 A055661 A055662
Sequence in context: A093147 A066410 A116508 this_sequence A123816 A015691 A027775
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KEYWORD
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nonn
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AUTHOR
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Paolo Dominici (pl.dm(AT)libero.it), Jun 07 2000
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