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Search: id:A105494
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| A105494 |
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Number of partitions of {1,...,n} containing 4 strings of 3 consecutive integers such that only v-strings of consecutive integers can appear in a block, where v = 1,2,3. |
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+0
3
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| 5, 75, 855, 8665, 83485, 788515, 7424515, 70378930, 675685240, 6594991405, 65598204272
(list; graph; listen)
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OFFSET
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12,1
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COMMENT
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Partitions enumerated by A105486 in which the maximal length of consecutive integers in a block is 3.
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REFERENCES
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A. O. Munagi, Set Partitions with Successions and Separations, Int. J. Math and Math. Sc. 2005, no. 3 (2005), 451-463
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LINKS
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A. O. Munagi, Set Partitions with Successions and Separations,IJMMS 2005:3 (2005), 451-463.
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FORMULA
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a(n)=Sum(w(n, k, 4), k=1...n), where w(n, k, 4) is the case r=4 of w(n, k, r) given by w(m, k, r)=w(m-1, k-1, r)+(k-1)w(m-1, k, r)+w(m-2, k-1, r)+(k-1)w(m-2, k, r) +w(m-3, k-1, r-1)+(k-1)w(m-3, k, r-1) r=0, 1, ..., floor(n/3), k=1, 2, ..., n-2r, w(n, k, 0)=sum(binomial(n-j, j)*S2(n-j-1, k-1), j=0..floor(n/2)).
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EXAMPLE
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a(12)=5, the enumerated partitions are (1,2,3,7,8,9)(4,5,6,10,11,12),
(1,2,3,7,8,9)(4,5,6)(10,11,12), (1,2,3)(4,5,6,10,11,12)(7,8,9),
(1,2,3,10,11,12)(4,5,6)(7,8,9), (1,2,3)(4,5,6)(7,8,9) (10,11,12).
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CROSSREFS
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Cf. A105486, A105490, A105493.
Sequence in context: A127212 A091903 A105490 this_sequence A030986 A091882 A034688
Adjacent sequences: A105491 A105492 A105493 this_sequence A105495 A105496 A105497
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KEYWORD
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more,nonn
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AUTHOR
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A. O. Munagi (amunagi(AT)yahoo.com), Apr 11 2005
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