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Search: id:A080010
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| A080010 |
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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=2, r=3, I={1}. |
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+0
1
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| 1, 1, 1, 3, 9, 19, 38, 84, 193, 430, 940, 2074, 4609, 10223, 22611, 50022, 110780, 245348, 543189, 1202511, 2662417, 5894961, 13051820, 28897016, 63979205, 141653762, 313629217, 694390210, 1537413824, 3403913006, 7536438344
(list; graph; listen)
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OFFSET
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0,4
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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)+2*a(n-3)+3*a(n-4)+3*a(n-5)-2*a(n-6)-a(n-7)-a(n-10) G.f.: -(x^5+x^3+x^2-1)/(x^10+x^7+2*x^6-3*x^5-3*x^4-2*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: A014540 A115238 A005994 this_sequence A135117 A038163 A075188
Adjacent sequences: A080007 A080008 A080009 this_sequence A080011 A080012 A080013
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KEYWORD
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nonn
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AUTHOR
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Vladimir Baltic (baltic(AT)galeb.etf.bg.ac.yu), Feb 10 2003
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