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A084874
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Number of (k,m,n)-antichains of multisets with k=3 and m=2.
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0
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0, 0, 9, 162, 2025, 21870, 219429, 2112642, 19847025, 183642390, 1682955549, 15327821322, 139038251625, 1257873017310, 11360034454869, 102475388237202, 923689006041825, 8321664254958630, 74945757885541389, 674816499677616282
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| By a (k,m,n)-antichain of multisets we mean an m-antichain of k-bounded multisets on an n-set. A multiset is called k-bounded if every its element has the multiplicity not greater than k-1.
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LINKS
| Goran Kilibarda and Vladeta Jovovic, Antichains of Multisets, J. Integer Seqs., Vol. 7, 2004.
Index to sequences with linear recurrences with constant coefficients, signature (18,-99,162).
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FORMULA
| (1/2!)*(9^n - 2*6^n+3^n).
G.f. -9*x^2 / ( (6*x-1)*(3*x-1)*(9*x-1) ). - R. J. Mathar, Jul 08 2011
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CROSSREFS
| Cf. A016269, A047707, A051112-A051118, A084869-A084883.
Sequence in context: A023039 A159831 A133793 * A158749 A133681 A157553
Adjacent sequences: A084871 A084872 A084873 * A084875 A084876 A084877
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KEYWORD
| nonn
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AUTHOR
| Goran Kilibarda, Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 10 2003
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