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Search: id:A080012
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| A080012 |
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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={0}. |
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+0
1
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| 1, 0, 1, 2, 6, 11, 23, 51, 113, 244, 526, 1142, 2483, 5389, 11687, 25358, 55034, 119430, 259151, 562340, 1220276, 2647993, 5746085, 12468857, 27057165, 58713537, 127407187, 276470942, 599936262, 1301849496, 2824986880, 6130163753
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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) = 2a(n-2)+3a(n-3)+4a(n-4)+5a(n-5)+a(n-6)-2a(n-7)-a(n-8)-a(n-9)-a(n-10) G.f.: -(x^5+x^3+x^2-1)/(x^10+x^9+x^8+2*x^7-x^6-5*x^5-4*x^4-3*x^3-2*x^2+1)
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CROSSREFS
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Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A085264 A005999 A102429 this_sequence A103143 A005673 A084308
Adjacent sequences: A080009 A080010 A080011 this_sequence A080013 A080014 A080015
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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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