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Search: id:A079959
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| A079959 |
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Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=1, r=5, I={2,4}. |
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+0
1
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| 1, 1, 2, 3, 6, 10, 19, 33, 60, 106, 191, 340, 610, 1089, 1950, 3485, 6236, 11150, 19946, 35670, 63802, 114107, 204091, 365018, 652857, 1167652, 2088402, 3735179, 6680529, 11948378, 21370166, 38221375, 68360472, 122265404, 218676571
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OFFSET
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0,3
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COMMENT
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Number of compositions (ordered partitions) of n into elements of the set {1,2,4,6}.
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REFERENCES
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D. H. Lehmer, Permutations with strongly restricted displacements. Combinatorial theory and its applications, II (Proc. Colloq., Balatonfured, 1969), pp. 755-770. North-Holland, Amsterdam, 1970.
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FORMULA
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Recurrence: a(n) = a(n-1)+a(n-2)+a(n-4)+a(n-6) G.f.: -1/(x^6+x^4+x^2+x-1)
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CROSSREFS
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Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A089985 A007473 A014595 this_sequence A028495 A136752 A093126
Adjacent sequences: A079956 A079957 A079958 this_sequence A079960 A079961 A079962
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KEYWORD
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nonn
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AUTHOR
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Vladimir Baltic (baltic(AT)matf.bg.ac.yu), Feb 19 2003
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