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A080004
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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={-1,2}.
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0
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1, 1, 1, 2, 4, 9, 15, 25, 46, 84, 156, 280, 501, 909, 1647, 2990, 5408, 9773, 17695, 32033, 58000, 104976, 189968, 343860, 622409, 1126617, 2039201, 3690898, 6680644, 12092173, 21887215, 39616409, 71706406, 129790404, 234923948
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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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LINKS
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Table of n, a(n) for n=0..34.
Vladimir Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics Vol. 4, No 1 (2010), 119-135
Index to sequences with linear recurrences with constant coefficients, signature (1,0,1,1,4,-1,1,0,-1,-1).
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FORMULA
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a(n) = a(n-1)+a(n-3)+a(n-4)+4*a(n-5)-a(n-6)+a(n-7)-a(n-9)-a(n-10).
G.f.: -(x^5-1)/(x^10+x^9-x^7+x^6-4*x^5-x^4-x^3-x+1)
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CROSSREFS
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Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A026036 A072846 A157254 * A176915 A060742 A060737
Adjacent sequences: A080001 A080002 A080003 * A080005 A080006 A080007
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KEYWORD
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nonn
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AUTHOR
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Vladimir Baltic, Feb 10 2003
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STATUS
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approved
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