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Search: id:A080001
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| A080001 |
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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={-1,0,2}. |
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+0
1
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| 1, 0, 0, 1, 1, 1, 1, 2, 4, 3, 4, 8, 10, 13, 16, 24, 36, 43, 59, 85, 115, 156, 207, 289, 401, 533, 729, 1002, 1368, 1864, 2526, 3465, 4740, 6436, 8785, 11995, 16375, 22331, 30420, 41550, 56705, 77296, 105456, 143874, 196321, 267792, 365216, 498356
(list; graph; listen)
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OFFSET
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0,8
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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-3)+a(n-4)+2*a(n-5)-a(n-9)-a(n-10) G.f.: -(x^5-1)/(x^10+x^9-2*x^5-x^4-x^3+1)
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CROSSREFS
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Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A087794 A050514 A133702 this_sequence A136743 A011387 A019656
Adjacent sequences: A079998 A079999 A080000 this_sequence A080002 A080003 A080004
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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 10 2003
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