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A079960
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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=5, I={2,3}.
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0
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1, 1, 2, 3, 5, 9, 16, 28, 49, 85, 148, 258, 450, 785, 1369, 2387, 4162, 7257, 12654, 22065, 38475, 67089, 116983, 203983, 355685, 620208, 1081457, 1885737, 3288160, 5733565, 9997618, 17432848, 30397660, 53004405, 92423790, 161159378
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Number of compositions (ordered partitions) of n into elements of the set {1,2,5,6}.
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REFERENCES
| 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
| Recurrence: a(n) = a(n-1)+a(n-2)+a(n-5)+a(n-6) G.f.: -1/(x^6+x^5+x^2+x-1)
G.f.: 1/(1-z-z^2-z^5-z^6). [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 17 2009]
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MAPLE
| g:=1/(1-z-z^2-z^5-z^6): gser:=series(g, z=0, 49): seq((coeff(gser, z, n)), n=0..35); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 17 2009]
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CROSSREFS
| Cf. A002524-A002529, A072827, A072850-A072856, A079955-A080014.
Sequence in context: A137402 A134009 A018160 * A005314 A099529 A088352
Adjacent sequences: A079957 A079958 A079959 * A079961 A079962 A079963
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KEYWORD
| nonn
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AUTHOR
| Vladimir Baltic (baltic(AT)matf.bg.ac.yu), Feb 19 2003
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