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Search: id:A079958
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| A079958 |
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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={3,4}. |
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+0
1
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| 1, 1, 2, 4, 7, 13, 25, 46, 86, 161, 300, 560, 1046, 1952, 3644, 6803, 12699, 23706, 44254, 82611, 154215, 287883, 537408, 1003212, 1872757, 3495988, 6526172, 12182800, 22742368, 42454552, 79252477, 147945385, 276178586, 515559248
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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 {1,2,3,6}.
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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-3)+a(n-6) G.f.: -1/(x^6+x^3+x^2+x-1)
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CROSSREFS
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Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A102113 A034440 A000074 this_sequence A018082 A018083 A108361
Adjacent sequences: A079955 A079956 A079957 this_sequence A079959 A079960 A079961
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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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