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Search: id:A080000
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| A080000 |
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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={-1,1,2}. |
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+0
1
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| 1, 1, 1, 1, 1, 2, 3, 5, 7, 9, 12, 16, 24, 35, 50, 70, 96, 135, 190, 270, 383, 539, 759, 1065, 1500, 2116, 2985, 4212, 5932, 8356, 11770, 16585, 23381, 32953, 46445, 65445, 92216, 129951, 183129, 258091, 363719, 512566, 722316, 1017886, 1434445
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OFFSET
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0,6
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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)+2*a(n-5)-a(n-6)+a(n-7)-a(n-10) G.f.: -(x^5-1)/(x^10-x^7+x^6-2*x^5-x+1)
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CROSSREFS
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Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A126256 A062438 A102424 this_sequence A032459 A028870 A057886
Adjacent sequences: A079997 A079998 A079999 this_sequence A080001 A080002 A080003
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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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