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Search: id:A079969
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| A079969 |
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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}. |
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+0
1
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| 1, 1, 2, 3, 6, 11, 21, 38, 70, 128, 236, 434, 799, 1469, 2702, 4969, 9140, 16811, 30921, 56872, 104604, 192396, 353872, 650872, 1197141, 2201885, 4049898, 7448923, 13700706, 25199527, 46349157, 85249390, 156798074, 288396620, 530444084
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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 {1,2,4,5,6}.
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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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FORMULA
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Recurrence: a(n) = a(n-1)+a(n-2)+a(n-4)+a(n-5)+a(n-6) G.f.: -1/(x^6+x^5+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: A030037 A077078 A077079 this_sequence A034064 A034074 A018175
Adjacent sequences: A079966 A079967 A079968 this_sequence A079970 A079971 A079972
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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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