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Search: id:A079992
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| A079992 |
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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=3, r=3, I={-2,2}. |
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+0
1
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| 1, 1, 2, 3, 9, 19, 49, 100, 233, 503, 1166, 2580, 5884, 13092, 29622, 66281, 149569, 335524, 755737, 1697149, 3819301, 8582469, 19306314, 43397191, 97600441, 219421360, 493425528, 1109386496, 2494606984, 5608933040, 12612101201
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OFFSET
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0,3
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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)+3*a(n-2)-a(n-3)+a(n-4)+a(n-5)+3*a(n-6)-5*a(n-7)-9*a(n-8)+a(n-9)+a(n-10)+a(n-11)-a(n-12)+a(n-13)+a(n-14) G.f.: -(x^2-1)*(x^6+x^4+x^3+x^2-1)/(x^14+x^13-x^12+x^11+x^10+x^9-9*x^8-5*x^7+3*x^6+x^5+x^4-x^3+3*x^2+x-1)
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CROSSREFS
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Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Adjacent sequences: A079989 A079990 A079991 this_sequence A079993 A079994 A079995
Sequence in context: A089753 A094679 A094812 this_sequence A106519 A006866 A121908
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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 17 2003
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