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A079966
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={0,2}.
0
1, 0, 1, 0, 2, 1, 4, 2, 7, 5, 14, 12, 27, 26, 53, 57, 106, 122, 212, 258, 428, 543, 868, 1135, 1766, 2364, 3605, 4910, 7374, 10175, 15109, 21054, 30998, 43513, 63656, 89851, 130817, 185416, 268984, 382436, 553308, 788520, 1138525, 1625356, 2343253
OFFSET
0,5
COMMENTS
Number of compositions (ordered partitions) of n into elements of the set {2,4,5,6}.
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.
LINKS
Vladimir Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics Vol. 4, No 1 (2010), 119-135.
FORMULA
a(n) = a(n-2)+a(n-4)+a(n-5)+a(n-6).
G.f.: -1/(x^6+x^5+x^4+x^2-1).
KEYWORD
nonn,easy
AUTHOR
Vladimir Baltic, Feb 19 2003
STATUS
approved