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Search: id:A056243
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| 1, 9, 41, 146, 456, 1312, 3568, 9312, 23552, 58112, 140544, 334336, 784384, 1818624, 4173824, 9494528, 21430272, 48037888, 107020288, 237109248, 522715136, 1147142144, 2507145216, 5458886656, 11844714496, 25618808832, 55247372288
(list; graph; listen)
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OFFSET
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3,2
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REFERENCES
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Hwang, F. K.; Mallows, C. L.; Enumerating nested and consecutive partitions. J. Combin. Theory Ser. A 70 (1995), no. 2, 323-333.
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FORMULA
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a(n)=sum_{0<=j<=n-3} (-1)^(n-3-j)*binomial(n-3, j)*binomial(n+2j-1, 2j), for n>=3. - Pab Ter (pabrlos2(AT)yahoo.com), Nov 06 2005
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MAPLE
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seq(add((-1)^(n-3-j)*binomial(n-3, j)*binomial(n+2*j-1, 2*j), j=0..n-3), n=3..40); # first T:=proc(n, k) local j: if k=1 then 1 elif k<=n then add((-1)^(k-1-j)*binomial(k-1, j)*binomial(n+2*j-1, 2*j), j=0..k-1) else 0 fi end: seq(T(n, n-2), n=3..40); # 2nd (Pab Ter)
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CROSSREFS
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Sequence in context: A018836 A001846 A034441 this_sequence A083584 A146239 A083085
Adjacent sequences: A056240 A056241 A056242 this_sequence A056244 A056245 A056246
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KEYWORD
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nonn,easy
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AUTHOR
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Colin L. Mallows (colinm(AT)research.avayalabs.com), Aug 23 2000
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EXTENSIONS
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More terms from Pab Ter (pabrlos2(AT)yahoo.com), Nov 06 2005
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