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Search: id:A079975
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| A079975 |
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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=1, r=4, I={3}. |
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+0
1
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| 1, 1, 2, 4, 7, 14, 26, 49, 93, 175, 331, 625, 1180, 2229, 4209, 7949, 15012, 28350, 53540, 101111, 190950, 360613, 681024, 1286127, 2428875, 4586976, 8662591, 16359466, 30895160, 58346092, 110187694, 208091537, 392984789, 742159180
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OFFSET
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0,3
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COMMENT
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Number of compositions (ordered partitions) of n into elements of the set {1,2,3,5}.
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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)+a(n-2)+a(n-3)+a(n-5) G.f.: -1/(x^5+x^3+x^2+x-1)
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CROSSREFS
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Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A088813 A097596 A054191 this_sequence A076739 A017996 A024502
Adjacent sequences: A079972 A079973 A079974 this_sequence A079976 A079977 A079978
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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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