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A079965
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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={0,3}.
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0
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1, 0, 1, 1, 1, 3, 3, 5, 8, 10, 17, 24, 35, 54, 77, 116, 172, 252, 377, 555, 822, 1220, 1801, 2671, 3953, 5849, 8666, 12823, 18987, 28113, 41612, 61615, 91214, 135037, 199929, 295976, 438193, 648734, 960420, 1421893, 2105059, 3116482, 4613879, 6830695
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OFFSET
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0,6
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COMMENTS
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Number of compositions (ordered partitions) of n into elements of the set {2,3,5,6}.
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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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LINKS
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FORMULA
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a(n) = a(n-2)+a(n-3)+a(n-5)+a(n-6).
G.f.: -1/(x^6+x^5+x^3+x^2-1).
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MATHEMATICA
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LinearRecurrence[{0, 1, 1, 0, 1, 1}, {1, 0, 1, 1, 1, 3}, 50] (* Harvey P. Dale, Jul 10 2017 *)
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CROSSREFS
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KEYWORD
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nonn,easy,changed
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AUTHOR
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STATUS
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approved
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